Some 15 days after transplant, tomato seedlings at a
commercial farm near Immokalee, Fla. suffered the effects of
hurricane Frances on 5 Sept. 2005. Though many producers were
forced to reapply plastic mulch and replant their fields after each
of the major storms of the season, Charley, Frances, Ivan, and
Jeanne (McElroy, 2004), some growers were able to nurse their
damaged plantings back to health. This report documents injury,
growth, and yield of hurricane-damaged tomato plants under
large-scale commercial conditions in southwest Florida.
Frances caused by far the greatest damage to plants
discussed in this report because of sustained high winds in the
Immokalee area (Fig. 1). Winds from Frances reached 80 mph,
similar to Charley and Jeanne, but winds from Frances were more
persistent than that of the other storms. Plants that survived were
rated 24 Sept. and labeled for further observation according to
arbitrary categories of size and apparent vigor: best, good, fair,
and poor (Fig. 2). Plants rated poor, which were small and stunted,
were not included in this study because they were not expected to
survive or produce marketable fruit. Ten plants of each category
were removed from beds by hand with roots intact to record injury
and root and shoot dry mass. In addition, ten other plants of each
category were labeled in the field for future observations of injury
recovery, yield, and final shoot and root dry weight.
Plants exposed to hurricane winds exhibited varying
amounts of damage depending on their general and specific location
on the farm. Plants were severely damaged in areas located near
cypress hammocks, on the leeward side where winds apparently
tumbled downward and violently after passing over the treetops.
In other areas of the farm, plants were not as seriously damaged
but the damage they sustained varied from plant to plant without
any obvious pattern. Plants rated best were located randomly next
to plants of all other categories: best, good, fair, or poor. It was
clear, however, that when damage occurred, injury was located
on a section of stem just below the soil line and appeared to be
the result of plants being whipped around in the planting hole by
strong winds (Fig. 3). Injury was minor on plants rated best, with
callous forming around relatively small areas of wounding and
only a few roots forming above the injured areas (Fig. 4a and b).
In contrast, injury was relatively severe on plants rated fair, with
callous forming around wounded areas and, in addition, loss of
stem tissue and many roots forming above the injured areas in
response to damage sustained by these plants (Fig. 4c and d).
Plants injured by Frances and rated best produced
significantly more early yield and larger fruit at first harvest than
plants rated good or fair (Table 1). At second harvest, however,
plants rated good produced more extra-large sized fruit than plants
rated best. Total yields for the second harvest were not significantly
different among any of the treatments. Plants rated best and

sampled 34 days after transplant (19 days after Frances) exhibited
significantly more shoot and root dry mass than plants rated good
or fair, but as with yield data, these differences disappeared later
when plant shoot and root dry mass was recorded at the end of the
study (data not shown). In addition, plants harvested at the end
of the study showed stems with varying amounts of internal stem
discoloration. (Fig. 5b and d) There was a tendency among plants
rated best to have less internal discoloration than plants rated fair,
but there was too much variation among best, good, and fair to
draw firm conclusions. By the end of the study, sections of stem
below the original injury on some plants appeared to have rotted
and decomposed. These plants appeared to have lost their original
roots, roots that were intact at transplant and soon thereafter, and
these plants were relying later in the growing season solely on
roots that had developed above the injury (Fig. 5a and c).
Upon reflection, it was a wise decision by the production
manager of this farm to nurse hurricane-damaged plants back to
health rather than replant the field. Early yield from these plants
occurred during a time when market prices were high, about $30
per 25-lb box of green mature extra-large fruit for the first harvest
and $40 per box for the second (Fig. 6). These prices would not
have been captured if the field had been replanted. Prices at the
time of the third harvest were still high but declining rapidly.
Commercial harvest of the field precluded recording data from
the third harvest.
It was observed that the farm's normal water, fertilizer, and
pest control programs were adjusted in response to the needs of the
damaged crop. First, moisture content of plant beds was increased
to ensure that roots arising from above the damaged areas of plant
stems, located at or near the surface of the plant bed, would not
dry out. Second, a complete nutrient mix was applied via drip
irrigation because it was assumed that plants with damaged stems
and roots could not easily acquire nutrients already present in the
plant bed. Third, the farm's pest control program was adjusted
to minimize further damage caused by opportunistic pathogens
invading fresh wounds and weakened plants.
The rating system used in this research-best, good, and
fair-was an arbitrary rating system based on obvious differences
among individual plants at the beginning of the study. In addition,
it cannot be known how damaged plants would perform compared
to those not damaged by hurricane-force winds. Despite these
limitations, it is clear that the amount of damage sustained by
individual plants varied greatly according to location-general
location on farm and specific plant-to-plant location. Plants rated
best produced higher early yields than plants rated fair. Yields of
plants rated good and fair appeared to recover, but yields appeared
delayed compared to that of plants rated best.
In conclusion, tomato plants can sustain a surprising
amount of wind injury and still recover (Cleugh et al., 1998; Greig
et al., 1974; Precheur et al., 1978), producing high yields when
growing conditions are carefully managed. Damage to plants
was highly localized in an area of stem tissue just below the soil
surface. As injury increased, early yields decreased. Early yield
of extra-large sized fruit was especially sensitive to the amount
of injury sustained. After the third harvest, all plants appeared to
recover and significant differences in shoot or root growth were
not detected among plants rated best, good, or fair. Finally, plants

described in this report were mostly affected by hurricane Frances.
Plants on the same farm and located less than a mile away were
affected to a greater extent by Jeanne. Winds of this storm not
only caused the kind of injury reported here but also a more severe
breaking and kinking of stems (Fig. 7).

Table 1. Yield of first and second harvests of hurricane-damaged tomato plants from a commercial field. Hurricane Frances
occurred 15 days after transplant. First and second harvests occurred 79 and 93 days, respectively, after transplant.

zPlants were visually rated at the beginning of the study and divided into three categories according to apparent growth and vigor: best,
good, and fair.
Y Values in columns followed by different letters are significantly different at Ps0.05. Values are means of ten replications.

-3-

Cull
(no./plant)

10 a
7a
3a

Fruit wt.
(oz)

8.4 a
8.3 a
6.4 b

6.0 a
6.5 a
6.2 a

2 60
SIvan

S40

20

10 20 30 10 20
August September

Figure 1. Wind speed at Immokalee, Fla. during August
and September 2004 and recorded by an automated
weather system (fawn.ifas.ufl.edu) every 15 min at
a height of 33 ft. There were four named hurricanes
during this period.

Figure 3. Young tomato plant after being whipped around in the planting hole by hurricane force winds.

Poor

Figure 2. Rating of hurricane-damaged tomato plants
according to plant size and apparent severity of injury at
the beginning of the study.

Figure 4. Rooting, stem damage, and callous formation on tomato plants rated best and fair 34 days after transplant and
19 days after hurricane Frances. Shown is plant rated best before (a) and after (b) roots removed and plant rated fair
before (c) and after (d) roots removed. Plants rated good (not shown) were intermediate to those rated best and fair. Soil
line indicated by white arrow, callous tissue by gray arrow.

Figure 5. Rooting and stem damage on tomato plants rated best (a and b) and fair (c and d) after third harvest and end
of study. Plants rated good (not shown) were intermediate to those rated best and fair. Note discoloration in stems due
to original wind injury and apparent infection by soil pathogens (b and d).

-7-

50
Extra large
Large
40 I ------ Medium
Xr
5 30

i 20 -_

1st harvest
10 2nd harvest
3rd harvest

0
Oct'04 Nov'04 Dec'04 Jan'05

Figure 6. Prices for mature green tomatoes per 25-lb box, US #1 grade, during the period when plants in this study were
evaluated and harvested, 2004 to 2005. (Source: F. Roka, personal communication, compiled from USDA/AMS Market
News Reports).

Figure 7. Tomato plants on the same farm that escaped injury by hurricane Frances but were later damaged by hurricane
Jeanne.

ABSTRACT
Southwest Florida is an important production area for
winter fresh-market tomatoes with more than 20,000 acres
planted annually. The tomato production system in SW Florida
(Collier and Hillsborough/Manatee County), which generally
includes raised beds, polyethylene mulch and drip irrigation, has
been very effective in producing high tomato yields. But, with
the development of nutrient best management practices (BMPs)
for vegetable crops, N recommendations must be high enough
to ensure economical yields, but not excessive to minimize the
environmental impact of tomato production. The current UF-
IFAS N fertilization rate of 200 lbs/acre ofN (with supplemental
fertilizer applications under specified conditions) may need
to be increased according to tomato growers. Therefore, the
objectives of the project were to establish partnerships with
selected SW Florida tomato growers to evaluate the effects of
N applications in yield, plant growth, petiole N sap, insects
and disease incidences. Nine on-farm trials were conducted
during 2004 and 2005. Treatments consisted of N fertilizer
rates from 200 to 400 lb/acre under seepage and drip irrigation.
Nitrogen rates did not affect tomato biomass 30 and 60 days
after treatment (DAT), except in the drip trial 60 DAT. Petiole N
was higher than the UF-IFAS range in the seepage trials, but not
in the drip trial. Yield and financial impacts varied across trials.
In all trials except trial six, total production of extra large (5x6)
cartons was greater under the higher grower fertilization rate.
Total revenue was greater on all experiment sites, even in trial
six. Since treatment plots were harvested regardless of market
prices, it must be noted that revenue differences for the fall trials
were overstated. When prices fall below $5 per carton, growers
will choose either to abandon the crop, or direct harvesting crews
to pick only the extra large sizes (5x6s). Trial six illustrated an
important lesson of market timing. While the 200 lb N/acre rate
on trial six produced more total cartons of 5x6s, 5x6 yields from
the grower standard plots were greater during the third harvest
date, April 19, when the market price exceeded $19 per carton.
This project is continuing to study the effects of these treatments
over the next two years.

INTRODUCTION
The vegetable production system in Florida, which
typically incorporates raised beds, polyethylene mulch, drip or
seepage irrigation and an adequate quantity of N-P-K, has been
very effective in producing high vegetable yields (Hochmuth et
al., 1998). But, nitrogen (N) fertilizer management has become an
issue ofenvironmental concern for Florida vegetable growers under
the adoption by the State of vegetables BMPs (Best Management
Practices). The BMP manual for vegetables endorses UF-IFAS
recommendations of 200 lb/acre of N in tomatoes (Lycopersicon
esculentum Mill.) (plus provisions for supplemental fertilizer
applications), K20 rates of 225 lb/acre for soils 'very low' in
Mehlich 1 potassium, and rates of P20, ranging from 0 to 150
lb/acre for soils testing very high and very low, respectively
(Maynard et al., 2003). In addition to 'basic' fertilizer applications,
supplemental fertilizer applications are allowed for tomato in the
UF-IFAS recommendations (Simonne and Hochmuth, 2005)
and in the BMP manual (Simonne and Hochmuth, 2003) under
three situations. When a UF-IFAS irrigation recommendation
is followed, supplemental fertilizer applications are allowed (1)
after a leaching rain (defined as 3 inches in 3 days or 4 inches
in 7 days) for crops (including tomato), (2) under extended
harvest season, and (3) plant nutrient levels (leaf or petiole) fall
below the sufficiency range. Nutrient management in tomato
production is not limited to the total amount of fertilizer found
in the recommendation. Together with rate, the effectiveness of
nutrient management depends on fertilizer placement, source,
growing season, irrigation methods and application time. With
drip irrigation, typical fertilization practices consist of applying
25% of the total N and K2O rates broadcast in the bed, while 100%
of P20, and micronutrients are applied pre-plant. The remaining
75% of bothN and KO2 are injected through the drip tape. In some
cases, a fertilizer wheel is also used to supply additional fertilizer.
For tomato grown with seep irrigation, approximately 25% of the
fertilizer is applied broadcast in the bed (bottom or 'cold mix').
The rest of the fertilizer is applied in two bands on the shoulders
of the bed ('hot mix'). Water rising by capillarity slowly dissolves
the fertilizer band and supplies nutrients to the crop. In some cases,
the fertilizer wheel is also used for supplemental fertilization.
Recent unpublished surveys by IFAS personnel indicate
that most growers do not follow IFAS nutrient recommendations,
particularly for N. Major growers' critique of current IFAS
nutrient management includes the lack of large scale on-farm
field research in southwest Florida, lack of N recommendation
for drip irrigated tomato crops of more than 13 weeks duration,
introduction of new varieties that support greater crop yields, and
a direct correlation between higher N rates and lower incidence
of plant diseases. Many growers believe that UF-IFAS fertilizer
recommendations are too low to produce economical yields,
especially during wet years. On many operations, N rates are
reported to be 150% of the UF- IFAS recommended rate. In some
cases, N rates used may be as high as 200% of the UF-IFAS N
recommendation. In addition, growers admit they tend to apply
irrigation in excess of crop evapotranspiration (ETc), which is the
recommended water management practice. Although N runoff
has not been identified as a widespread problem in south Florida,
the environmental concern remains that the combination of over-

fertilization and excessive irrigation may contribute to elevated
nutrient concentrations in ground and surface waters.

MATERIALS AND METHODS
Ten fertility trials were conducted during the 2004-2005
growing season on farms that not only included 16,000 acres or
80% of staked tomato production in Southwest Florida (Collier
and Hillsborough/Manatee County), but also well represented
the diversity of growing conditions in the area: six trials were
done with seepage and four with drip irrigation. Six trials were
conducted in the fall 2004 and four in the spring 2005. Trials also
included different varieties (mostly 'Florida 47' and 'Sebring'),
plant densities (in-row spacing of 18 to 24 inch/plant; 5 or 6 ft bed
centers), soil type (Immokalee and Myakka fine sand), and farm
size (100 to 5,000 acres). Treatments consisted of N fertilizer
rates ranging from 200 to 418 lb/acre, with each trial including
at least the UF-IFAS rate (200 lb N/acre) and the grower's rate
(typically higher than the UF-IFAS rate). Plots size varied from
0.1 to 50 acres (Table 1).
Data collection: On 30 and 60 days after transplanting
(DAT), the shoots of three tomato plants (fruits removed) selected
randomly in each treatment were collected and oven dried at
65oC until constant weight to determine dry matter accumulation
(Mills and Jones, 1996). Beginning at first flower buds and
continuing until third harvest, fresh petiole sap NO3-N and K
concentrations were measured weekly using ion-specific meters
(Cardy, Spectrum Technologies, Inc., Plainfield, IL). Monitoring
wells were constructed from a 4-ft long, 4-inch diameter PVC
pipe screened at the bottom 8 inch (Smajstrla, 1997). A float was
attached to one end of a 0.75-inch PVC pipe to serve as the water
level indicator. The float-0.75 inch PVC pipe assembly floated
freely inside the 4-inch well. Permanent marks were made at
every 1 inch to indicate the water table depth below the plastic
mulch bed. Weekly observations of the ground water table depth
were taken throughout the growing season. The number of plants
showing symptoms of Fusarium crown rot (caused by Fusarium
oxysporum fsp. radicis-lycopersici) in each harvest plot was
counted weekly in trial 1 between 12 Jan. and 2 Feb. Weekly
counts of all adult whiteflies (Bemisia argentifolii) were made on
10 top fully expanded leaves from 10 randomly selected plants in
3 locations in each plot at four trials (replicates). Analysis of the
mean number of whiteflies counted in each plot over each 7-day
interval was accumulated to give an estimated value of whiteflies
x days for each plot. An analysis of variance (ANOVA) over all

replicates (farms) was conducted by considering only the highest
and lowest N rate treatments (designated "high" and "low") for
those farms where more than 2 rates were tested.
Harvest was done by the project's crew on at least six plots
in each treatment following commercial practices. Harvest plots
contained 10 plants each, and were 15 to 22 ft long, and were
clearly marked to prevent unscheduled harvests by commercial
crews. Marketable tomatoes were graded in the field according to
USDA specifications of number and weight of extra-large (5x6),
large (6x6), and medium (6x7) fruit (USDA, 1997). The number
of plots harvested in experiment five was twelve. There were no
true replications, but within each field the within-plot variability
of yield components was compared to the across-plot variability
using ANOVA and mean separation using the Duncan's Multiple
Range Test at the 5% level. In the Manatee/Hillsborough trial,
entire plots (3 rows X 80 ft) were harvested and graded. (Data
is not included here due to late harvest but can be obtained from
authors.)
The economic section of this paper calculates a monetary
value by fertilizer treatment for each farm site. The values compare
projected total revenues gained by fertilizer treatment utilizing
yield data and market prices reported at the date of each harvest
(USDA-AMS, 2005). The purpose of the economic calculations
was not to document actual losses or gains, but to illustrate some
of the economic issues associated with N fertilization decisions.
Southwest Florida tomato growers harvest mature-green tomatoes
in two market windows fall/winter and early spring. It is
important to realize that grower prices for the fresh tomato are set
on a daily basis and are sensitive to total market supplies. Tomatoes
imported from Mexico, Europe and Canada, compete with those
from Southwest Florida for the same market windows.

RESULTS AND DISCUSSIONS
Plant growth: There were no differences in plant biomass
30 and 60 DAP for all experiments and seasons, except experiment
four 60 DAP (Table 2). For trial four growers N rates produced a
higher tomato biomass than 250 lb/acre. Therefore, N rates had
little effect on tomato biomass 30 and 60 DAP
Fresh petiole sap analysis: Changes in petiole sap NO-
N and K concentrations were different with seepage and drip
irrigation, but tended to be above the IFAS sufficiency threshold
for all experiments, N treatments and at all stages of plant growth
(Figure la and b). Measurements of tomato sap N03-N and
K were higher in the highest N rates than in lower N rates, but
higher than their sufficiency range for all stages of plant growth.
Measurements of tomato sap K were more stable than sap N03-N
during the season. In the Hillsborough/Manatee trial, both N03-N
and K readings were higher than sufficiency thresholds season-
long with differences in N03-N among treatments only evident
just prior to third harvest.
Water tables: The average water table depths among the
experiments with seepage irrigation system varied from 18 to 22
in. The maximum fluctuations in the water table depths among
treatments within a farm were observed for experiment 1 (Figure
2a) where the water table varied from 11 to 24 in during the fall
growing season. For experiments with drip irrigation system the
average water table depths varied from 23 to 37 in. The lower

-9-

water table depth for the drip irrigated farms was expected since
irrigation is mainly provided with the drip systems. The fluctuations
in water table among the drip irrigated experiments were highest
at experiment 4 where the water table varied from 32 in to 11 in.
An unusually high water table in late December (Figure 2b) was
probably due to a 0.6 in rainfall which occurred on December
25, 2004. Such occasional high water table conditions are mostly
unavoidable and are to be expected in Southwest Florida. Overall,
the water table depths among different treatments were relatively
stable.
Disease incidence: In trial one, the symptoms ofFusarium
crown rot first appeared on 12 Jan. 05. The number of plants
showing symptoms increased through 2 Feb 05 (Fig. 3). The
plants in the plots with the lowest N rate of 200 lb N/acre had
the highest amount of disease incidence with an average of 53%
symptomatic plants. The other three treatments receiving 236,260
or 260+ biosolids lb N/acre, had 10%, 27%, and 20% average
disease incidence, respectively. These observations support
grower's observations and suggest that plant nutritional status may
influence the susceptibility of tomato to diseases such as Fusarium
crown rot. These results support the need to include the incidence
of diseases in the selection of practical fertilizer rates. However,
N rate may need to be associated with factors in determining
the incidence of Fusarium crown rot symptom because such an
association was not observed in all the trials. In the Hillsborough/
Manatee trial, the major disease problem was bacterial speck, but,
surprisingly, no differences were observed between treatments.
Whitefly counts: More adult-whitefly days were observed
on plants receiving the highest N rate as compared to the lowest N
rate (Fig. 4). The trend was consistent among all four individual
farms (replicates) and statistically significant over all farms F =
30.6, df = 1, 19, P < 0.01. Nitrogen in the form of amino acids
is the limiting resource for sternrrhynchous homoptera including
whiteflies. Amino acids are concentrated by these phloem feeders
through excretion of water and sugars as honey dew. Whitefly
adults are known to prefer leaves and plants with higher N
concentrations that correspond to higher amino acid titers in the
phloem (Bentz et al., 1995). Positive response of adult-whitefly
day to N fertilization has also been observed on cotton (Gossypium
hirsutum) in the field (Bi et al., 2005).
Economic Analysis: Many tomato growers in Southwest
Florida believe that they would incur significant financial losses
if they limited N fertilization rates to 200 lb N/acre. They believe
that a 50 percent increase in the N-rate would support higher
production levels and allow them to fully take advantage of
favorable market prices. In other words, they view higher N-rates
as a form of insurance. Most prices presented in the price history
of US# 1 tomatoes corresponding to all the harvest dates during
the 2004-05 N trials (Table 3) were higher for the larger sizes
(5x6s). Under high price market conditions, the price difference
between 5x6s and 6x7s increased. When the market prices fell to
low levels, there was no price difference between extra large and
medium sized tomatoes. Most of the fall trials were harvested
during January 2005, a time when the market was at historic low
prices. Between the end of December and mid-March, tomato
prices were below an estimated break-even price of $9.50 per
25-lb box (UF-FRE, 2003). More importantly, a price of $4 per

25-lb box or below does not even cover harvest, packing, and
marketing costs. Consequently, many fields were picked once
for the 5x6 size and then abandoned. For the purpose of data
collection, grower-cooperators allowed field trials to be picked
three times regardless of the commercial market conditions. By
the latter part of March, prices rebounded and the market for
southwest growers remained strong for the rest of the spring
season. Abandoning fields for economical reasons may result in
increased residual fertilizer levels left in the field at the end of the
season. This may not be an environmental concern for N as it may
be denitrified during the summer flooding of the fields (Simonne
and Morgan, 2005).
Table 4 summarizes for each trial the impact of N rate
differences within a trial on 5x6 yields and total revenue. In trial
one, four N-rate treatments were evaluated. On the remaining farm
sites, only two N-rates were considered, the "grower-standard"
and an IFAS rate of 200 lb N/acre. For example, the "grower-
standard" on trial three was 300 lb N/acres, or a difference of 100
lb N/acres between "grower-standard" and IFAS rate. A monetary
value of yield differences was calculated on the basis of the
projected yield differences between N rate treatments and prices
listed in Table 4 that corresponded to the actual harvest dates of
a given trial.
Yield and financial impacts varied across trials. In all trials
except trial six, total production of extra large (5x6) cartons was
greater under the higher grower fertilization rate. Total revenue
was greater on all experiment sites, even in trial six. Since
treatment plots were harvested regardless of market prices, it
must be noted that revenue differences for the fall trials were
overstated. When prices fall below $5 per carton, growers will
choose to either abandon the crop, or direct harvesting crews
to pick only the extra large sizes (5x6s). Trial six illustrated an
important lesson of market timing. While the IFAS rate in trial six
produced more total cartons of 5x6s, 5x6 yields from the grower
standard plots were greater during the third harvest date, April 19,
when the market price exceeded $19 per carton.
It is important to emphasize that the yield data presented
in this paper are the first of a three-year study. There is ongoing
discussion and analysis as to whether or not the yield differences
between the fertilization rates are statistically significant. As the
data are pooled over several years, statistical differences should
become more apparent. Even if the experimental design of this
study does not allow for the discernment of statistical differences,
a trend has already appeared within the first year data. That is,
higher fertilization rates from the various "grower-standard"
treatments produce more total revenue. It is a trend that reinforces
the economic reasoning behind the observed behavior of tomato
growers pushing for higher N fertilization rates.
What cannot be incorporated into this analysis are the
environmental risks associated with off-site movement of
nutrients such as N. Whether N is an environmental hazard in
southwest Florida is a debatable issue. However, regardless
of perspective, environmental costs are currently not a part of
a grower's decision-making process. If N proves to be a real
environmental threat, then public policy, either through regulation
or incentive payments, will be needed to force changes in N
fertilization rates beyond the direct impact to production.

- 10 -

Extension and Education: Grower's were highly engaged
in the project and strong successful partnerships were developed
throughout the fall 2004 and spring 2005 growing seasons.
Growers provided input in determining fertilizer rates and helped
apply the treatments. Weekly visits throughout the growing season
by project leaders were organized to discuss progress toward the
goals and to review in-season weekly progress reports. These
weekly progress reports were farm-by-farm reports of sap petiole
analyses, water table depth, dry matter accumulation, and yield.
Additionally, growers received a final report at the end of the
season.
Educating farm employees on nutrient management issues
was also an important part of the project. For example, one
employee on three farms was trained in the use of cardy-N and K
meters to monitor sap NO3-N and K plant nutrient management,
and to interpret the results. Growers agreed that this tool was a
simple, practical way to monitor plant nutritional status.

SUMMARY FOR THE 2004-2005 SEASON:
Results from these first-year trials are encouraging and
indicate that this project is on track to achieve its objectives:
1. On farm trials along with extensive one-on-one grower
contact was an effective means to engage growers in
the implementation and outcome of this research and
demonstration project
2. N recommendation for tomato is not a simple "one size
fits all". Recommendations should consider irrigation
method (seepage or drip irrigation) and growing season
(early, mid or late plantings requiring from 15 to 20
weeks from plating to harvest), and position of the bed
relative to irrigation (adjacent v-ditches or increasingly
further away)
3. In-season tomato nutritional status monitoring provides
a real-time tool for assessing plant fertilizer needs
4. For a relatively dry year like the 2004-2005 season,
grower's rate resulted in significantly greater early 5x6
yields in 2 out of 7 trials (29% of the cases)
5. Education is needed for drip-irrigation growers and a
Drip Irrigation School should be organized in southwest
Florida

Outlook for the 2005-2006 Season:
1. All participating growers intend to participate next
season
2. Growers want to add early plantings (August) to the
current planting window (October-February)
3. Interest in conducting similar trials with grape tomato
(a rapidly expanding segment of the tomato industry
in south Florida for which no specific fertilizer
recommendations exist)
4. Automated soil moisture monitoring equipment will be
installed at three seepage-irrigated sites next season
5. Bed position in relation to the v-ditch will be taken into
account

Vegetables need water, mineral elements, oxygen, carbon
dioxide, light and time to complete their life cycle and produce
economical yields. Vegetables also need to be protected from biotic
(disease, pests, nematodes, mammals) and abiotic (heat, drought,
flood, wind) stresses. Hence, vegetable production requires the
use of a wide range of products (also called "production inputs")
which include water, fertilizers, fungicides, insecticides, and soil
fumigants. The composition of these products is well defined and
they have a clear role in vegetable production, as well as a clear
mode of action. In contrast, a wide array of production inputs has
less defined roles and modes of action. Typically, these production
inputs are stimulatorss" or "growth enhancers" of some sort (Table
1). These production inputs are affectionately referred to as "snake
oils" although "biostimulant" should be used. The objectives of
this paper are to (1) highlight the origins of the "snake oils", (2)
identify warning signs, (3) provide guidelines for conducting on-
farm trials to test efficacy of biostimulants, and (4) provide a brief
summary of biostimulant research in Florida.
The term "snake oil" was originally used to describe a type of
19th century patent medicine sold in the United States that claimed
to contain snake fat, supposedly an American Native remedy for
various ailments. Clark Stansley's snake oil tested by the federal
government in 1917 was found to contain mineral oil, 1% fatty oil
(presumed from beef), red pepper, turpentine, and camphor. This
product did not contain snake parts, but its formulation resembles
that of modem-day capsaicin-based liniments. "Snake oil" became
rapidly a synonym of "quack" or fraudulent medicine, and was
used to describe a worthless preparation fraudulently peddled as
a cure for many ills. In this historical context, labeling a product
as a "snake oil" implied an intention to deceive. By extension,
"snake oil" is used today to describe products that have no clear
use or that can be easily replaced in areas as diverse as computer
cryptography, medicine, insurance, or engine treatment products.
This term has also found its way into the agricultural vocabulary.
The conventional wisdom defines "snake oil" as a product that
may help crop production. In this paper, the term "snake oil" is
used only to describe a class of products, and does not imply any
intention by any party involved to engage in a deceptive practice.
While defining biostimulant is difficult, "snake oils" share
common characteristics: they seldom hurt plants, they usually
don't help, they cost money, and they always make the user feel
better. When growers consider using a production input, the two
most important points they consider first are price and efficacy.
The old motto "you get what you pay for" often helps justify a
hefty price and creates the willingness to buy almost any product.
Warning signs that a product may be a "snake oil" include (1) sales
language that states or implies "Trust us, we know what we are
doing", (2) the impossibility to know what is in the product under
the pretext of "old proven secret recipe", (3) the abundant use

of invented terms (technobabble), obscure jargon, or trademarked
terms that confuse rather than explain, (4) claims of "revolutionary
breakthrough", or (5) most important, unsubstantiated claims
So if the warning signs are so easily recognizable, how
did "snake oils" get associated with agriculture and vegetable
production? Some reasons may include (1) the perennial
attractiveness of what is "new" and "improved", even at the expense
of proven efficiency; (2) failure of proven practices that trigger an
immediate and desperate search for alternatives; (3) decision based
on emotions rather than on facts; and, (4) the fear of a customer to
show ignorance by not understanding an obscure, complex lingo
used to describe a product and its benefits. Clearly, the best remedy
against disappointment is information and education.
Products that (1) have been tested by not-for-profit
organizations such as public universities, (2) have an established
mode of action, (3) are efficient over a defined range of
circumstances, and (4) are reasonably priced, may not be "snake
oils" and may be worth using (Trenholm, 2003). In the absence of
reliable information, the best alternative to test a biostimulant's
efficacy is to try it under the conditions of its intended use: in the
field, with a crop. Field trials should be well defined, large enough,
representative, and fair. The purpose of a field trial should be well
defined. Doing so will help develop a valid protocol that really
puts the product to the test. Moreover, a clear purpose will help
assess the mode of action. Trials involving few plants may not
reflect field variability, thereby yielding erroneous conclusions.
Trials should include areas where products are tested and a control
area. Having a control helps isolate the effect of that product alone,
since the only difference between the treated area and the control
is the application of the product tested. Ideally, trials should
replicated. Trials should be conducted in a "real" field, not in an
area of the farm where growing conditions are less than optimal.
Areas such as row ends, low spots, and shady areas should be
avoided. Data collected should be simple, and relevant to the set
objectives. Identifying before the trial begins where/how/when
the trial will be conducted will help ensure the trial is valid, and
the conclusions are reliable. Results of well-conducted on-farm
trials will yield trustworthy information about the efficacy, but at
times will not reveal the composition and therefore the mode of
action of the product. As the conventional wisdom admits if
you do not know how a product works, you won't find out why it
does not work".
Biostimulant research with vegetables has a long history in
Florida(see additional resources section). Most products evaluated
were foliar or soil-applied fertilizers. Their intended effect on
vegetable crops is typically to promote plant growth of high-
value crops such as tomato (Lycopersicon esculentum), pepper
(Capsicum annuum) or strawberry (Fragaria x Annassassa).
Collectively, research results can be summarized as inconsistent
from year to year, better performance under stressful conditions,
and generally too expensive for regular use. In contrast, soil
applications of humate-based products did not increase root length
ofred maple (Acer rubrum L.), but they increased sap flow (Kelting
et al., 1998). In a pot experiment, green bean (Phaseolus vulgaris)
mean pod fresh weight responded to algal treatment (Russo and
Berlyn,1992). Overall, the literature contains a few isolated
reports of positive effects of biostimulants. It is unfortunate that

-17-

the vast majority of research conducted on biostimulants aims at
testing the efficacy of a formulation (sometimes undisclosed). The
projects aim at finding out if the product works, or if it does not.
In either case, few attempts are made to understand the reasons
why the products worked or did not. Hence, current work on
biostilmulant is somewhat like short-term product testing. An
alternative approach would be to start with a formulation, optimize
it, and develop an understanding of the role of each ingredient.
Unfortunately, this long-term, costly approach is not commonly
used. Until then, we'll have to expect miracles from SOS.

Tew, J.A. and D.C. Ferree. The influence of a synthetic foraging
attractant, Bee-ScentTM, on the number of honey bees visiting
apple blossoms and on subsequent fruit production. Ohio State
Res. Bull. 299-99, http://ohioline.osu.edu/rc299_2.html

Comments
Foliar fertilization with
inorganic nutrients is a well
documented practice. UF/
IFAS recommendations for
foliar fertilization support the
application of micronutrients,
especially on alkaline soils
(Simonne and Hochmuth,
2004)
The need for bees to pollinate
vegetables, especially
cucurbits, is well documented
(Sanford, 1992). Scientific
studies have demonstrated
the efficacy of bee attractants
(Malerbo-Souza et al., 2004;
Tew and Ferree, 1998). In
commercial fields, bee behavior
is affected by many factors
including bee attractants.
Source of carbon, water,
terminal acceptors of electrons
are among the compounds
needed for microbiological
growth. Many of the ingredients
found in these formulations are
needed for microbe growth.
The long-term positive effect
of organic matter on soil
microorganism populations is
well documented.
Soil amendments applied at
rates in the range of few tons
per acre may be more efficient
than formulations applied at
rates in the range of a few pints
per acre.
Modifying soil structure or
soil water holding capacity
are targeted, possible soil
improvement measures.
Regeneration and restoration
are noble goals that need to be
better defined if they are to be
reached

z Mention of products and web sites are made for illustration and educational purposes only and do not represent a recommendation
or endorsement by UF/IFAS of these products over similar ones. Consult EDIS (at www.edis.ifas.ufl.edu) for current UF/IFAS
recommendations
Y Information from the manufacturer's or distributer's web site

Persistent rainfall and generally wet conditions create
a high risk for microbial problems in tomato fruit. With high
day-time temperatures, wet weather creates an almost explosive
situation where growers and handlers cannot successfully get
their crop to market because of decay. Anecdotal reports have
suggested that water chlorination practices may be adequate or
even excessive and still fail to prevent decay if the fields are wet.
In contrast, prior to wide spread adoption of water chlorination,
packinghouses routinely packed, shipped and marketed tomatoes
without incurring major fruit losses, particularly during the
drier times of a season. Below, we describe some of the factors
that appear to be responsible for decay during wet weather and
sometimes in association with mishandled fruit.
Most, if not all, decay outbreaks, where rot incidence
exceeds grade standards but wound incidence is below those
standards, can be traced back to a water congestion of the fruit
surface. Water congestion means that fruit cell sap and water
permeate openings (=pores) on the fruit surface. These openings
are connected with a system of air spaces intercellularar spaces)
that enable cells inside a fruit to exchange CO2 for 02. Sufficient
gas exchange to support living cells cannot occur through more
than a few mm of cell sap or water (Burton, 1974). The air spaces
in all types of fruit, and, indeed, in all types of plant tissues are
connected to pores in the plant surface. Certain structures, such
as the hydathodes of leaves, are open pores that enable the
plant to expel excessive water in the familiar guttation process
(Curtis, 1943). Another type, the stomata, are closed in darkness
but open in response to light to allow exchange of 02 for CO2 in
photosynthesis.
Virtually every type of pore on the plant surface can
become water congested creating what has been called a water
channel that connects the plant's internal environment with that
existing externally (Johnson, 1947). Water placed on a water
channel frequently moves into the plant tissues, either in response
to capillary forces or transpiration (moisture loss by the tissues).
The water movement can carry particulates including the carbon
particles in India ink and various bacteria including the gram
positive cocci of Staphlycoccus aureous, an animal pathogen
and gram negative rods such as various plant pathogenic bacteria
(Diachun et al., 1944). This movement occurs quite rapidly with
rates measured in seconds to minutes (Johnson, 1947).
The pores on a tomato fruit are mostly in the stem scar where
most of the gas exchange occurs (Brooks, 1937). The connective
or white tissues within the stem scar include cells arranged with
a myriad of air spaces and pores. These cells form an abscission
layer as the fruit matures. Additionally, a vascular system is
present in bundles arranged in a ring around the outside of the

stem scar. When a fruit is harvested, the cells on the abscission
layer normally separate cleanly, whereas those in the vascular
bundles are mechanically separated, meaning torn apart.
A stem scar is not highly permeable to water, particularly
when it's dry. However, water can enter these tissues through a
purely physical process called infiltration (Bartz and Showalter,
1981). Additionally, water has been observed to enter vascular
tissues in the stem scar, perhaps analogous to a flower stem. A
water soluble dye flooded into the stem scar of a fruit picked during
a rain shower was observed to move in delicate threads (likely
xylem vessels) in the walls of the fruit. The torn cells around the
vessels in the vascular bundles also appear to be a point of entry
for water. Usually, however, direct penetration of the cells in a
stem scar does not occur unless the fruit was physically treated to
ensure a pressure imbalance between the air within and that outside
the fruit. Two different physical phenomena can cause a sufficient
pressure imbalance for infiltration. The cooling of a warm tomato
that is submerged in water leads to a reduction in air pressure in
the fruit's intercellular spaces (Bartz and Showalter, 1981). The
resulting partial vacuum can draw water through the stem scar
into the fruit. The direct pressure of water on the stem scar surface
can also cause an infiltration (Bartz, 1982). This water pressure
can result from a hydrostatic force such as with immersion depth
or from a direct impact with water such as in dump tanks or where
heavy streams of water are applied to unload gondolas.
The infiltration of fruit by water, usually defined as a weight
increase > 0.1 g, is usually associated with a high risk ofpostharvest
decay. However, the manner by which infiltration occurs and the
presence of free chlorine in the water affect that risk. Cooling
fruit from 35 to 20oC with an aqueous cell-suspension of soft rot
bacteria in a shower hydrocooler at 10C produced 50 to 100%
decay over a 10-day 20oC storage period (Vigneault, et al., 2000).
However, when chlorine was added to the suspension before it was
used to cool the fruit (50 to 200 mg/L of free chlorine at pH 7.0),
the fruit remained free of decay throughout the storage period.
By contrast, when tomatoes were infiltrated with cell suspensions
plus free chlorine (150 mg/L, pH 6.8) during immersion depth
experiments, up to 22% of the fruit developed soft rot during a
12-day storage at 24oC (Bartz, 1988). Thus, infiltration from direct
contact with water is a much greater hazard than that associated
with temperature change.
Water congestion of the stem scar apparently can occur in
the absence of a detectable fruit weight increase. The importance
of this to postharvest decay is unknown. Spray inoculation of the
freshly exposed stem scar of 320 fruit of eight different breeding
lines and cultivars with soft rot bacteria, led to less than 10%
decay (adjacent to stem scar) by the time the fruit were table
ripe. However, none of the 320 control fruit developed lesions
adjacent to the stem scar. Conditions were dry and hot at the time
of harvest, which are not conducive to decay.
Several factors affect how much water is absorbed when
fruit are submerged in water, cooled in water, dropped into water
or struck by a stream of water. Water absorption is greatest
in green and least in table ripe fruit. Pinks and breakers fall in
between. Fresh stem scars absorb more than those that are 24-
hr old. Moreover, as the stem scar dries, water intrusion is less
likely to occur. Fruit harvested with stem scars attached decrease

-20-

in water uptake tendencies at about the same rate as fruit pulled
cleanly from the plant. Thus, it appears that residual moisture in
the stem scar and not a fresh separation scar is more important to
water uptake.
Cultivars exposed to the same immersion depth or
temperature differential in water differ in water uptake (Bartz,
1991). The differences tend to be consistent among different fields
and planting dates. After harvests of Jay Scott's breeding line test
in Bradenton, Spring, 2004, fruit of Florida 91 and 47 absorbed
more water than several other entries (Table 1). This difference was
consistent over two harvests of the plots. 'Sebring' and 'Soraya'
absorbed the least water. In a later planted "soft rot" test, Florida
91 and 47 were again the highest, whereas Sebring was the lowest
(Table 2). Here, fruit from one harvest was separated into two
groups. One group was tested for water uptake at 4 h after harvest
and a second at 24 h after harvest. The rankings were generally
similar although Sanibel and Solar Fire were not as receptive to
water at 24 h. In a similar "soft rot" test at Quincy, Florida MH-1
ranked the highest whereas Peto 882, a Roma cultivar was the
lowest (Table 3). Florida 47 and Florida 91 again ranked high,
whereas Sebring and Solar Fire were lower. Fruit from the second
harvest absorbed more water than those from the first. Significant
rainfall had fallen between the two harvests and we had to dodge
water puddles during the second harvest. Two groups of fruit
samples were evaluated at the second harvest, one at 5 and the
other at 22 h after harvest (Table 4). The relative rankings did not
change between the two tests. Finally, this past Spring (2005),
Solar Fire was the highest for water uptake, whereas Florida 47
and Florida 91 appeared intermediate (Table 5). Amelia was the
lowest. Weather conditions at harvest were dry and hot. There was
no standing water.
The level of applied nitrogen significantly affected water
uptake for 'Amelia' versus 'Florida 47' in four recent tests (Spring
2004 and Spring 2005) conducted by Drs. George Hochmuth, Jr.
and Steve Olson-two at Live Oak and two at Quincy. However,
the differences in uptake attributed to cultivar and to time after
harvest were much larger than those associated with N level. Plots
fertilized with the highest H level, 350 lbs/ac did not produce fruit
that absorbed the most water.
In general, fruit size is correlated with tendency to absorb
water. Thus, cultivars that produce larger fruit can be expected
to absorb more water. This tendency complicates cultivar
comparisons. Expressing weight increase as a percentage of fruit
weight eliminates some but not all fruit-size bias. However, the
critical factor is how much water is absorbed. Fruit aren't likely to
decay if they haven't absorbed water.
Warm fruit absorb water more readily than cool fruit (Bartz,
1981). The reason for this is unknown. Warm fruit contain less air
than cool fruit because of the difference in gas density. As such,
the air in warm fruit may be more easily compressed. However,
once water enters the surface of the stem scar it appears to be
under capillary forces. Flooding the surface with additional water
produces water intrusion likely until the pressure of trapped air is
sufficient to counteract the capillarity.
When fruit absorb water during packinghouse handling,
microbes on the stem scar are internalized as discussed above.
Additionally, the water channels in congested stem scars enable

rapid infiltration by any water that contacts the scar surface. With
water congested stem scars, dump tank or flume water can readily
enter the fruit during the 30 to 60 seconds that it floats in the
flumes. Whether fruit harvested during wet conditions have water
congested stem scars is unclear.
Holding fruit overnight before packing them should reduce
their water uptake tendencies for two reasons. First, the stem
scars would start drying and secondly, some of the field heat
would dissipate, thereby reducing the direct tendency of the fruit
to absorb water and also reducing the amount of heating required
to prevent infiltration due to fruit cooling. Holding fruit overnight
does increase the decay hazard, because damaged and diseased
fruit can produce inoculum that can contaminate sound fruit. Soft
rot lesions can develop among warm fruit within 24 h, but they
usually are small, particularly if the fruit are cooled to 20C. The
development of large lesions and partially decayed fruit such as
found in major outbreaks normally requires a minimum storage
period of 48 to 72-h depending on temperature. Thus, the decay
hazard associated with holding fruit in field bins or gondolas
overnight may be reduced if field crews can be trained to avoid
harvesting partially decayed fruit or if such fruit are not found on
the plants.

'Within 24 h of harvest, tomatoes were submerged in water and exposed to a simulated immersion depth of 4 feet for 2 min.
b Values not followed by the same letter were significantly different at P=0.05 by the Waller/Duncan Multiple Range Test.

'Within 4 or 24 h of harvest, tomatoes were submerged in water and exposed to a simulated immersion depth of 4 feet for 2 min.
bValues not followed by the same letter were significantly different at P=0.05 by the Waller/Duncan Multiple Range Test.

aWithin 24 h of harvest, tomatoes were submerged in water and exposed to a simulated immersion depth of 4 feet for 2 min.
bAt 5 and 22 after harvest, tomatoes were submerged in water and exposed to a simulated immersion depth of 4 feet for 2 min.
bValues not followed by the same letter were significantly different at P=0.05 by the Waller/Duncan Multiple Range Test.

SAt 5 or 22 h of harvest, tomatoes were submerged in water and exposed to a simulated immersion depth of 4 feet for 2 min.
b Values not followed by the same letter were significantly different at P=0.05 by the Waller/Duncan Multiple Range Test.

SWithin 24 h of harvest, tomatoes were submerged in water and exposed to a simulated immersion depth of 4 feet for 2 min.
b Values not followed by the same letter were significantly different at P=0.05 by the Waller/Duncan Multiple Range Test.

Bacterial leaf spots associated with tomato have primarily
been bacterial spot incited by Xanthomonas campestris pv.
vesicatoria and bacterial speck incited by Pseudomonas syringae
pv. tomato. In Florida, bacterial spot is the most destructive
bacterial disease when high temperatures and excessive moisture
occur during fall crops (Pohronezny and Volin, 1983). Bacterial
spot is considered a warm weather pathogen and thus in the spring
it would not be as aggressive as in the fall. Generally bacterial
leaf spot in Florida is not a significant concern to spring crops of
tomato because of the typically dry weather.
Bacterial speck is favored by relatively cool weather
conditions such as occurred this past spring season. Therefore, it is
the more likely candidate to be associated with a spring epidemic.
Bacterial speck has been a problem in Florida tomato production
during periods of significant rainfall during spring production.
Jones and Jones (1983) identified several tomato fields in Manatee
County where bacterial speck was a major problem in a spring
tomato crop. That particular year was cool and extremely wet.
In the past bacterial speck has been a chronic problem in the
Homestead area during winter tomato production to a large extent
because of the use of overhead irrigation.
The spring of 2005 was unusually wet and was conducive
for bacterial diseases. A number of fields were affected by what
was thought to be bacterial leaf spot. The fruit was also affected
although there it was unusual in appearance. The lesions were
large, sunken and distinctly black. They resembled bacterial
speck more than bacterial spot, although the lesions were
atypical in their rather large size (Figure la) unlike the "speck"
size lesions normally observed on the fruit. Large fruit lesions
caused by the bacterial speck pathogen, although rare, have been
observed previously in Florida by Dr. K. L. Pernezny (personal
communication). Although bacterial speck does occur frequently
on fruit, only very young developing fruit are susceptible.
Furthermore, it requires optimal conditions and inoculum for
infection as was demonstrated by Getz et al. (1983) for bacterial
speck and by Scott et al. (1989) for bacterial spot. In both studies
it was demonstrated that fruit infection only occurs during a short
time-frame following anthesis.
In order to conclusively show that this was bacterial
speck, isolations were made from lesions representing samples
from three fields. In all the lesion samples a bacterium was
present which was characteristic of the bacterial speck pathogen
(Pseudomonas syringae pv. tomato) and in a number of isolations
we recovered two types of organisms, the bacterial speck
pathogen and another one that was characteristic of the bacterial
spot pathogen (Xanthomonas campestris pv. vesicatoria).
The strains that were suspected of being the bacterial speck
pathogen were typical P. syringae pv. tomato strains based on
several bacteriological tests including fatty acid analysis. A

representative strain was used to inoculate young tomato plants.
Typical bacterial speck symptoms developed and confirmed that
this was the bacterial speck pathogen and not one of the weaker
pathogenic fluorescent pseudomonads that is often associated
with tomato. We determined the race for seven of the strains and
all were race 0 based on their ability to induce a hypersensitive
reaction following infiltration in Rio Grande-PtoR supplied by.
G. Martin (Boyce Thompson Institute, Ithaca, NY). Therefore
tomato genotypes carrying the Pto gene in all likelihood would
have been resistant to these strains.
We inoculated some very young fruit in the greenhouse to
determine if large fruit lesions could be reproduced. Young fruit
were inoculated by gently rubbing the bacterial suspension of one
of the P. syringae pv. tomato strains, one of the X. campestris pv.
vesicatoria strains and a mixture of both strains. The lesions on
fruit inoculated with the P. syringae pv. tomato strain only or the
mixture were large, sunken black lesions (Fig. 1B) very similar
to the field lesions, whereas lesions on the fruit inoculated with
the xanthomonad were small necrotic lesions, atypical of bacterial
spot lesions. Therefore, we conclusively demonstrated that P.
syringae pv. tomato can cause large speck lesions.
Control of bacterial spot and bacterial speck requires an
intensive program. Transplants must be free of bacterial diseases
going into the field. The fields also need to be isolated from
production fields from the previous season given that bacterial
cells can be transported long distances to infect healthy crops. It
is important to eliminate sources of inoculum such as volunteers
or adjacent fields as sources of inoculum. Bactericides are also
an important component of an integrated approach for controlling
bacterial diseases of tomato. Copper has been used for many
years and has been shown many times to be significantly more
effective if applied in a tank mix with an EBDC compound. A
second group of compounds that have proven effective are plant
activators. Actigard has been shown in many studies to reduce
bacterial spot and bacterial speck disease severity (Louws et al.,
2001). A very promising approach for controlling bacterial spot
has been to use bacteriophages (Flaherty et. al., 1999; Balogh et
al., 2001; Obradovic et al., 2004). We have demonstrated in the
field that bacteriophage applications result in significantly higher
fruit yields compared to the control or other standard treatments.
A similar strategy should be effective for controlling bacterial
speck.

Methyl bromide (MBr) alone, or in combination with
chloropicrin (Pic), has been the soil fumigant of choice since
the early 1970s (Overman and Martin, 1978), because of its ease
of use and high efficacy under a wide range of conditions. It is
typically shank-injected at 350 lb/acre to a soil depth of 10 inches
into raised beds that are simultaneously covered with LDPE
mulch. Standard LDPE is inexpensive and easy to use, but it is
highly permeable to MBr (Gamliel et al., 1998a, 1998b; Papiemik
and Yates, 2001; Williams et al., 1999; Yates et al., 1996a,
1996b). MBr has been classified as a substance that contributes to
depletion of stratospheric ozone. Consequently, a complete phase-
out of the use and production of MBr in developed countries
throughout the world was scheduled to occur by 2005, with
critical use exemptions permitted under the Montreal Protocol
(U.S. Environmental Protection Agency, 1999). Critical use
exemptions (CUE) are important for minor crops because growers
feel that an economically and technically viable MBr alternative
is not yet commercially available. However, even with permitted
exemptions, reduced rates of MBr may be needed to offset the
rising cost of the fumigant and to reduce atmospheric emissions.
Reduced emissions probably will be a requirement for future
CUEs.
To obtain a high degree of pest control with a fumigant, it is
necessary to maintain a sufficient quantity of fumigant gas in the
soil long enough to reduce the population of pests (Gamliel et al.,
1998b; Minuto et al., 1999). This might be accomplished by using
low rates of MBr under highly retentive or reduced permeability
film. Virtually impermeable film (VIF) is so named due to the much
higher fumigant retention capacity of this film compared to Idpe
and hdpe which have been the historical mainstays ofplasticulture.
VIF has become commercially available in recent years and is
much more retentive of fumigant gases than standard Idpe mulch
(Papiernik and Yates, 2001). This type of film increases fumigant
toxicity by increasing the duration of retention, which is caused by
a barrier polymer, such as ethylene vinyl alcohol or nylon, placed
between two layers of polyethylene (Papiernik and Yates, 2001).
Wang et al. (1997) determined that atmospheric emission of Mbr,
when covered with polyethylene for 5 days, declined from 64% of
applied MBr with conventional LDPE mulch to about 38% with
VIF. With the soil covered by VIF for more than 10 days, only 1%
to 3% of the MBr was lost.
In the past 6 years, considerable field research and
grower trials have been conducted with these VIF mulches in
Florida. Small plot studies demonstrated that nutsedge and stunt

nematodes could be controlled and crop yields maintained with
rates of methyl bromide / chloropicrin (67/33 formulation) as low
as one-fourth (88 lb./treated acre) of the standard use rate of 350
lb./treated acre when combined with some VIF mulch films, while
grower trials successfully established the commercial potential of
one-half normal rates (Gilreath et al, 2005a; Santos et al, 2005).
Additional research indicated that this improvement in fumigant
retention and control of soilborne pests with VIF was not restricted
to just methyl bromide, but also included 1,3-D-based fumigants
like Telone C-35 and Inline (Gilreath et al, 2004; Hochmuth et
al, 2003). Preliminary data indicate similar results with other
fumigants such as Midas.
Unfortunately, there are 2 drawbacks to most VIF products:
cost and handling characteristics. Today, all VIF is made in Europe
and must be imported, thus resulting in much higher cost than
standard film. Also, most of the VIF products are more difficult
to lay than standard films in that they are prone to linear sheer if
subjected to too much tension during laying. There is considerable
difference in handling characteristics among VIF materials, but
they are all based on polyamides, such as nylon, for their barrier
properties and these polyamides do not stretch well. Also, none
are embossed at the present time. High barrier films continue to be
evaluated as they become available, but to date Bromostop R VIF
has been the most consistent performer and appears to handle the
best under our conditions.
Recognizing the problems associated with some of the
existing VIF, we continue to search for other mulch films with
enhanced barrier properties. Over the past2 years, we have examined
the barrier properties of metalized films under field conditions, first
with 1,3-D (Inline) and more recently with methyl bromide. In
each case, application of Inline or methyl bromide in conjunction
with metalized film greatly increased the retention of the fumigant
(Gilreath et al, 2005b). In the case of methyl bromide, we were able
to obtain nutsedge control with 175 lb./acre of 67/33 under Canslit
R metalized film that was equal or superior to that obtained with
the full 350 lb./acre rate under standard Idpe or hdpe film in each of
four experiments. Bromostop R VIF was included in each of these
experiments and the field performance for gas retention under the
mulch film, as well as nutsedge control and fruit production, was
similar between Canslit R metalized film and VIF. Grower trials
with Canslit R metalized film confirmed these results. Additionally,
we determined that the retention of methyl bromide and resultant
nutsedge control with Canslit R metalized film was similar to what
we obtained with VIF at every rate of methyl bromide, ranging
from 88 to 350 lb./acre of 67/33.
While it is possible to use Bromostop VIF or Canslit
metalized film to reduce methyl bromide usage rates by one-
half, successful use involves more than just reducing gas flow and
laying mulch film. Methyl bromide has a high vapor pressure,
which means that at typical application temperatures it rapidly
becomes a gas and can do so even within the tubing and gas
knives of the application rig. This is an advantage for reduced rate
application, but it does not solve one inherent problem uniformity
of application. Typical gas rigs employ 3 knives per bed. A good
fumigation job requires that all 3 knives deliver the same amount
of product per minute so that the application rate is uniform in
the area being fumigated. When the rate is reduced, there is less

-26-

fumigant in the system and more opportunity for the formation of
bubbles as the methyl bromide "boils". This "boiling" easily can
be visualized by inserting small sight glasses in the application
equipment at the flow divider just ahead of the tubes which carry
the fumigant to the knives. Under normal conditions, a certain
amount of back pressure exists in the application system and can
be measured at the flow divider by installing a pressure gauge.
Application of a full 350 lb./acre rate will generate in excess of 30
psi of back pressure at this point. Reducing the methyl bromide
flow rate in order to deliver lower rates per acre will reduce
the back pressure measured at the flow divider. Our experience
indicates that back pressure below 15 psi results in nonuniform
distribution to the three knives which means inequalities in rate
across the bed. Usually the edges suffer the most and this effect
can be observed later in the season as poor control of nutsedge on
bed shoulders.
In order to increase back pressure when using low rates of
methyl bromide or any other fumigant, you must decrease the flow
capacity of the delivery system between the flow divider and the
gas knives. This can be accomplished in two ways. First, you can
use a smaller diameter tubing to deliver fumigant to the gas knives.
Standard gas rigs use tubing which is one-quarter inch inside
diameter. While this is fine for a gas with high vapor pressure like
methyl bromide or for high flow rates of other fumigants, it may
not be suitable in other situations. We have found that the use of
poly tubing ranging from one-sixteenth to one-eighth inch inside
diameter is necessary in order to achieve balanced or uniform
delivery of greatly reduced rates of methyl bromide. Tubing of
this size is not readily available, but it can be obtained and is an
important modification if a grower is going to use reduced rates
of methyl bromide with a highly retentive film like Canslit R
metalized or Bromostop R VIF. Fine tuning of flow capacity or
rate of any tube can be accomplished by increasing or decreasing
the length of the tube connecting the flow divider to the gas knife.
There is a certain amount of friction loss of flow within any size
tube and the effect of friction increases with increased length and
decreased tubing inside diameter. Typical length for one-sixteenth
and one-eighth inch tubing is 5 ft; although longer tubing has been
used when trying to achieve really low rates. Color coded tubing
is available which can be a big help when adjusting flow rates.
Yellow tubing has the thickest walls and smallest inside diameter
of one-sixteenth inch. Black tubing is available in one-eighth inch
inside diameter. These tubes all fit the same size connector, making
it easy to switch from one flow capacity to another. Select the tube
needed for the desired flow capacity, then once installed, adjust the
flow regulator valve for the required flow rate on the flow meter,
just like normal.
A second way to decrease flow and increase back pressure
is to use orifice plates (Teejet R flow regulators) in the tubing at
the top of the gas knife fitting. In order to use these plates, you
have to know what flow rate you need in each tube. Since the flow
rates of orifice plates are based on water, you have to do some
mathematical conversions to methyl bromide or choose one on the
high side and try it. In any event, you do not want a plate which
gives you the exact same flow rate as what you need; you want
one with a slightly higher flow rate so that clogging potential is
lowered. If you are going to use orifice plates, you should keep a

supply of various sizes on hand. The plates have numbers stamped
on them which tell you the size of the hole in the plate. Be sure to
keep your glasses handy because these can be hard to read. Orifice
plates work over a more narrow range of rates than tubing because
the restriction in flow occurs at one point rather than over a length
of tubing.
The system we use is commercially available (manufactured
by Mirruso Enterprises, Inc., available through Chemical
Containers, Inc.) and constitutes an easily installed, simple
modification. It consists of a flow divider with a small sight glass
for each knife, a 0 to 30 psi pressure gauge and small diameter
poly tubing. The sight glasses are equipped with standard quick
connect (insert friction connectors) couplings on top so the poly
tube easily can be connected and disconnected. Similar couplings
are located on the top of the gas knives. Sight glasses are useful
because they allow you to monitor flow and detect plugging of
chisels or lines. Plugging can be a significant issue with low rates
of fumigant. As a result, fumigant filtration is even more important
and filters need to be checked periodically and maintained clean
and free of trash to assure consistent flow through the fumigant
distribution system.
One thing to remember when using reduced rates of
fumigant: the flow rate has been greatly diminished so accuracy
and uniformity of delivery are critical. A common observation on
commercial farms is tractor movement as soon as the fumigant
flow valve is opened. There is a much longer delay in supplying all
the knives uniformly when the rate is reduced, so tractor movement
should not begin until all lines are fully charged. This condition
easily can be monitored by observing the sight gauges and back
pressure gauge. Once the back pressure stabilizes, fumigation can
begin. Addition of an inline check valve at the top of each gas
knife can be beneficial because it diminishes loss of fumigant
out of the line to the knife. By keeping the line full all the way
to the gas knife, there are fewer delays in fumigant delivery and
less time wasted purging air from lines. This would be especially
important for those growers who use radar controlled fumigant
delivery systems.
Rate reduction with methyl bromide works when combined
with a highly retentive mulch film like VIF or metalized film.
In addition to the use of the right film, success requires close
monitoring of fumigant delivery, assuring not only that the rate is
correct, but also that it is applied uniformly to all three knives in
the bed. Nonuniformity guarantees poor fumigant performance at
any rate, but with reduced rates of methyl bromide, the results can
be even more dramatic. The simple modifications described above
can greatly improve uniformity of delivery and performance. These
modifications are relatively inexpensive and are readily available
as a package. Before trying rate reductions growers should modify
their fumigation equipment to allow better control over uniformity
of flow. This can mean the difference between success and failure.
Under no conditions should a grower attempt to reduce his methyl
bromide rate by more than 50% of the standard use rate the first
time around. Rates lower than 50% are possible, but it is difficult to
achieve the required level of application uniformity and accuracy
without considerable experience and attention to detail. Growers
should gain experience with rate reduction and use of barrier films
because this will be the future and the future is now.

-27-

IMPORTANT FACTS TO CONSIDER
/ Not all VIF or metalized films are the same.
/ Gas retention with VIF mulch is fairly consistent among
manufacturers, but handling properties may differ greatly.
/ Gas retention among metalized films may vary by manufacturer.
Not all have been tested at this time.
/ One manifestation of non-uniformity of delivery of fumigant
may be nutsedge on the bed shoulders but not in the middle of
the bed.
/ Rate reduction requires close attention to uniformity of
application.
/ Uniformity requires balanced flow between all chisels or
knives.
/ Balanced flow requires sufficient back pressure on gas lines (at
least 15 psi at the flow divider).
/ Back pressure can be achieved by impeding flow at the
chisels.
/ Reduced flow rate at the chisel can be obtained by reduction
of line size (1/8th to 1/16th inch inside diameter) from the
flow divider to the chisel or by using Teejet ) flow regulators
(orifice plates).
/ Back pressure can be adjusted by selecting the length and inside
diameter of small diameter tubing from the flow divider to the
chisel or by selection of the proper size orifice plate based on
mathematical calculations.
/ Methyl bromide rates of 12 the normal 350 lb. / treated acre
rate generally require at least 5 ft of 1/8th inch inside diameter
tubing from the flow divider to each chisel.
/ Methyl bromide rates below 175 lb./treated acre may require 5
or more feet of 1/16 inch inside diameter tubing.

A new strain of Bemisia tabaci, "Q" biotype, was first
detected in the US on poinsettias purchased at a retail outlet
during December 2004 in Tucson by a team from the University
of Arizona. The plants were said to have been purchased from
a wholesale dealer in California. Although indistinguishable in
appearance from silverleafwhitefly, these insects proved markedly
less susceptible to pyriproxyfen, buprofezin, imidacloprid,
acetamiprid, and thiamethoxam. Electrophoresis, polymerase
chain reaction (PCR) and sequencing of the mitochondrial
cytochrome oxidase 1 gene revealed their unique genetic identity.
The debut of a new whitefly on poinsettia is reminiscent of a
scenario 19 years ago that culminated in unprecedented losses for
Florida tomato growers and a new pest pandemic. Are we in for an
equally devastating invasion?

History ofWhitefly Biotypes
Prior to 1986, B. tabaci, known as the sweetpotato
whitefly, was thought to be pretty much the same everywhere it
occurred throughout the tropics, subtropics and mild temperate
regions of the world. Then massive numbers suddenly turned
up in greenhouse poinsettias in Florida, spreading quickly to
field grown vegetables and other crops (Price 1987). Clouds of
whiteflies in tomato fields produced quantities of sooty mold and
a nuisance for pickers, followed by a new plant disorder, tomato
irregular ripening (Schuster et. al. 1990) and a new geminivirus,
Tomato Mottle (Polston and Anderson 1997). First dubbed the
"poinsettia" whitefly or even the "Florida" whitefly, it came to be
known as B. tabaci biotype "B" to distinguish it from the former
biotype "A". Biotype "A" had been relatively benign in Florida
but caused serious losses in California and Arizona as a cotton

pest and a vector of the "crinivirus" lettuce infectious yellows in
lettuce and melons (Duffus 1995).
The term biotypee" is synonymous with "strain" or even
"subspecies" and biotypes of the same species should be able to
produce fertile offspring when crossed. Although biotypes of B.
tabaci cannot be separated visually, biotype "B" was described in
1994, though not universally accepted, as a new species, Bemisia
atIgenrfitlii or silverleaff' whitefly (Bellows et. al. 1994). Species
status was conferred on the basis of biological differences such
as the ability to cause physiological disorders such as squash
silverleaf or tomato irregular ripening, as well as failure to produce
hybrids with biotype "A" whiteflies in the laboratory (Perring et.
al 1993).
Since the discovery of the silverleaf whitefly, numerous
other biotypes of B. tabaci have been described on the bases of
genetic differences at the molecular level and some biological
distinctions (Costa et al. 1991; Frohlich et al. 1999). These biotypes
form two main groups, New World types and Old World types.
The Old World types are more diverse, and often exhibit broader
host ranges that facilitate maintenance of high populations within
different agroecosystems, and movement of viruses among crops.
Old world types include the "B" biotype probably originating in
southwestern Asia, and the "Q" biotype that dominates in much of
the Mediterranean region (De Barro et al. 2005).

"B" VS "Q"
The "B" and "Q" biotypes are similar genetically and in
many of their biological characteristics. Both are major pests of
a wide range of crops including most vegetables. Both transmit
TYLCV, although "Q" is reported as a more efficient vector
than "B" (Sanchez-Campos et al. 1999). Both may also move
many other geminiviruses as well as a number of criniviruses
including tomato chlorosis and tomato infectious chlorosis
("TIC" and "TOC") (Jones 2003). However, there are also some
notable differences. "Q" only causes squash silverleaf and tomato
irregular ripening at very high infestation levels in contrast to "B".
On the other hand, Q appears to quickly evolve resistance to the
most commonly used insecticides for whitefly control (Cahill et
al. 1996a, 1996b). That means "Q" will probably out-compete
"B" under selective pressure from insecticides. Furthermore, the
resistance appears to be stable, meaning that it does not diminish
over time. However, resistance has its cost, and in the absence of

insecticides "B", with its presumably greater biotic potential, will
likely out-compete "Q" on most crops (Beitia et al. 1997). It may
also be true that "Q" is more readily attacked than "B" by certain
parasitic wasps, notably Eretmocerus mundus which was released
in the US from Spain (Stansly et al 2004, 2005). A similar species,
E. near emiratus has come be the dominant parasitoid attacking
B. tabaci in parts of Florida and California and would certainly
be a positive element in managing "Q". However, many of these
presumed differences, summarized in the table below, require
experimental confirmation.

LIKELY IMPACT OF BIOTYPE "Q" IN FLORIDA
The new biotype will certainly not reek anything like
the havoc that followed the last whitefly invasion. Biotype "B"
rapidly overwhelmed the old "A" biotype whitefly in Florida
and elsewhere with its ability to build up high populations on
numerous different crops. In contrast, "Q" would find itself faced
with well established populations of"B" on virtually any potential
host plant and may not compete effectively unless assisted by
insecticidal selection. Thus, Q might not achieve a foothold in
dooryard ornamentals but could in production greenhouses where
a captive whitefly population might be continually exposed to a
limited toolbox of products. Thus, the first control problems are
most likely to appear in the greenhouse/screenhouse ornamental
industry, as presaged by the find in Arizona.

WHITEFLY SURVEYS: PAST AND PRESENT
An extensive survey of B. tabaci populations in 15
economically important crops (including tomato) and 8 weed
species in Florida was conducted from March 2000 to May
2001 (McKenzie et al. 2004). Biotype analysis by RAPD/PCR
indicated the presence of only the B biotype of B. tabaci in all
collections. These data suggested that in Florida, the B biotype
of B. tabaci had excluded the native non-B biotypes (A biotype)
in agricultural ecosystems. Whitefly surveys were resumed in
2005 after the discovery of the "Q" biotype in California and
Arizona and figure 1 indicates the locations of sample sites by
county, past and present. Since the "Q" biotype was found in the
U.S., samples have been collected and analyzed in Florida from
Naples (Collier), Palm Bay (Brevard), Homestead (Dade), Parrish
(Manatee), New Port Richey (Pasco), Vero Beach (Indian River),
Tallahassee (Leon), andAltamonte Springs (Seminole). Currently,
only the B biotype has been detected in Florida. In cooperation
with APHIS, DPI, USDA-ARS and University researchers and
concerned growers across the state, extensive surveying of Florida
will continue to determine if the "Q" biotype has invaded Florida.
The goal of the survey is to first identify and then monitor apparent
movement of the "Q" biotype and predict downstream impacts
on crops and areas. The highest priority should be on sampling
greenhouses, and whitefly host crops in proximity to greenhouses
as well as retail outlets such as Home Depot. Knowing who and
where the enemy is has always been the foundation of a good IPM
program and should aide growers in making sound management
decisions.

ACTION PLAN
Soon after discovery in Arizona, an ad hoc Q-Biotype
Whitefly Taskforce was formed of interested scientists and
administrators from the regulatory and research communities.
Officials from USDA-APHIS Plant Protection and Quarantine
(PPQ) stated that their agency would apply the current policy for
the B-Biotype of the whitefly, Bemisia tabaci ("non-reportable/
non-actionable"), to the recently detected Q-Biotype. Thus, there
will be no specific federal barriers to movement of this pest. As yet
there has been no policy statement from Florida DACS-DPI, but it
seems unlikely that movement of whitefly-infested plant material
will be regulated in Florida either. However, both agencies are
cooperating in a national monitoring effort to track movement
of "Q" biotype, and so far (June 2005), there have been no new
reports of "Q" biotype in the US. Additionally, entomologists at
the Universities of Arizona and California have embarked on a
program to evaluate insecticide susceptibility of the "Q" biotype
populations in their respective states.
As movement of the new pest and associated control
problems become more apparent, additional research will be
directed at ways to mitigate the impact. Meanwhile growers
and consultants are advised to keep a sharp lookout for unusual
whitefly activity, and to apply even more rigorously the principals
of IPM and resistance management that have served us well in the
past. Mitigating the threat of biotype "Q" is just one more reason
to practice good IPM and resistance management practices: (1)
use insecticides only as needed based on scouting, (2) employ
alternate management strategies such as host free periods, clean
transplants, rouging of symptomatic plants, (3) limit exposure
of whiteflies to neonicotinoids by using only once in tomato
and abstaining if possible in other crops, (4) rotate classes of
insecticide. Sound insecticide management is our best insurance
against biotype "Q" and the increased threat of insecticide
resistance that it represents.

Variety selections, often made several months before
planting, are one of the most important management decisions
made by the grower. Failure to select the most suitable variety or
varieties may lead to loss of yield or market acceptability.
The following characteristics should be considered in
selection of tomato varieties for use in Florida.
Yield The variety selected should have the potential
to produce crops at least equivalent to varieties already
grown. The average yield in Florida is currently about
1400 25-pound cartons per acre. The potential yield of
varieties in use should be much higher than average.

Disease Resistance Varieties selected for use in Florida
must have resistance to Fusarium wilt, race 1, race 2 and
in some areas race 3; Verticillium wilt (race 1); gray leaf
spot; and some tolerance to bacterial soft rot. Available
resistance to other diseases may be important in certain
situations, such as Tomato Spotted Wilt and Bacterial
Wilt resistance in northwest Florida.

Horticultural Quality Plant habit, stem type and fruit
size, shape, color, smoothness and resistance to defects
should all be considered in variety selection.

Adaptability Successful tomato varieties must perform
well under the range of environmental conditions usually
encountered in the district or on the individual farm.

Market Acceptability The tomato produced must
have characteristics acceptable to the packer, shipper,
wholesaler, retailer and consumer. Included among
these qualities are pack out, fruit shape, ripening ability,
firmness, and flavor.

CURRENT VARIETY SITUATION
Many tomato varieties are grown commercially in Florida,
but only a few represent most of the acreage. In years past we have
been able to give a breakdown of which varieties are used and
predominantly where they were being used but this information is
no longer available through the USDA Crop Reporting Service.

TOMATO VARIETY TRIAL RESULTS
Summary results listing the five highest yielding and the five
largest fruited varieties from trials conducted at the University of
Florida's Gulf Coast Research and Education Center, Bradenton;
Indian River Research and Education Center, Ft. Pierce and North
Florida Research and Education Center, Quincy for the Spring
2004 season are shown in Table 1. High total yields and large fruit
size were produced by Fla. 8092, FL 47 and FL 91 at Ft. Pierce

and BHN 444 at Quincy. There was very little overlap between
locations. The same entries were not included at all locations.

TOMATO VARIETIES FOR COMMERCIAL
PRODUCTION
The varieties listed have performed well in University of
Florida trials conducted in various locations in recent years.

Plum Dandy. Medium to large determinate plants.
Rectangular, blocky, defect-free fruit for fresh-market production.
When grown in hot, wet conditions, it does not set fruit well and is
susceptible to bacterial spot. For winter and spring production in
Florida. Resistant: Verticillium wilt, Fusarium wilt (race 1), early
blight, and rain checking. (Harris Moran).

GRAPE TOMATOES
Grape tomatoes are elongated cherry type tomatoes with
very sweet fruit and fruit length about twice that of the diameter.
The fruit usually weigh about 1/3 to 12 oz. The plant habit and
fruit flavor are very similar to Sweet 100 and Sweet Million,
two old indeterminate cherry varieties. These varieties had

limited commercial use due to plant growth habit and severe fruit
cracking. The original 'grape' tomato variety was Santa, a high
quality indeterminate variety. Santa is a proprietary variety and has
limited availability. St. Nick is another indeterminate variety that
is available. There are also available several new indeterminate
varieties available but information is limited. Also on the market
are several determinate varieties such as Sweet Olive and Jolly
Elf, but flavor is not as good as the older indeterminates. There
are also new yellow and pink varieties available. Most of the grape
varieties are fairly resistant to fruit cracking.

REFERENCE
This information was gathered from results of tomato variety trials
conducted during 2004 at locations specified in each table.

Tomato variety evaluations were conducted in 2004 by the
following University of Florida faculty:

114 other entries had yields similar to Fla. 8224.
2 9 other entries had fruit weight similar to FL 91.
3 3 other entries had yields similar to Fla. 8135.
43 other entries had fruit weight similar to Fla. 8224.
5 23 other entries had yields similar to Amelia.
619 other entries had fruit weight similar to NC 0227.

Approximately 40,000 acres of tomatoes were harvested in
Florida during the 2003-2004 growing season. The value of the
fresh-market tomato crop that year was estimated at slightly above
$508 million (USDA, National Agricultural Statistics Service,
Vegetable Summary; http://jan.mannlib.corell.edu/reports/nassr/
fruit/pvg-bban/vgan0103.txt). The main areas of production are
Gadsden county (Quincy), the middle Suwanee Valley, Manatee
County (Palmetto-Ruskin), Hendry county (southeast cost), Palm
Beach county (southwest coast), and Dade county (Homestead).
All tomato production today uses plasticulture (transplants, raised
beds, stakes and polyethylene mulch). Tomatoes are irrigated with
drip or seepage irrigation.
Water and nutrient management are two important aspects
of tomato production in all these production systems. Water is
used for wetting the fields before land preparation, transplant
establishment, and irrigation. The objective of this article is to
provide an overview of recommendations for tomato irrigation
in Florida. Recommendations in this article should be considered
together with those presented in the "Fertilizer and nutrient
management for tomato", also included in this publication.
Irrigation is used to replace the amount of water lost by
transpiration and evaporation. This amount is also called crop
evapotranspiration (ETc). Irrigation scheduling is used to apply
the proper amount of water to a tomato crop at the proper time.
The characteristics of the irrigation system, tomato crop needs,
soil properties, and atmospheric conditions must all be considered
to properly schedule irrigations. Poor timing or insufficient
water application can result in crop stress and reduced yields
from inappropriate amounts of available water and/or nutrients.
Excessive water applications may reduce yield and quality, are a
waste of water, and increase the risk of nutrient leaching
A wide range of irrigation scheduling methods is used in
Florida, with corresponding levels of water managements (Table
1). The recommended method to schedule irrigation for tomato is
to use together an estimate of the tomato crop water requirement
that is based on plant growth, a measurement of soil water status
and a guideline for splitting irrigation (water management level 5
in Table 1). The estimated water use is a guideline for irrigating
tomatoes. The measurement of soil water tension is useful for fine
tuning irrigation. Splitting irrigation events is necessary when the
amount of water to be applied is larger than the water holding
capacity of the root zone

TOMATO WATER REQUIREMENT
Tomato water requirement (ETc) depends on stage of
growth, and evaporative demand. ETc can be estimated by
adjusting reference evapotranspiration (Eto) with a correction
factor called crop factor (Kc; equation [1]). Because different
methods exist for estimating ETo, it is very important to use Kc
coefficients which were derived using the same ETo estimation

method as will be used to determine ETc. Also, Kc values for the
appropriate stage of growth and production system (Table 2) must
be used.
By definition, ETo represents the water use from a uniform
green cover surface, actively growing, and well watered (such as
a turf or grass covered area). ETo can be measured on-farm using
a small weather station. When daily ETo data are not available,
historical daily averages of Penman-method ETo can be used
(Table 3). However, these long-term averages are provided as
guidelines since actual values may fluctuate by as much as 25%,
either above the average on hotter and drier than normal days, or
below the average on cooler or more overcast days than normal.
As a result, SWT or soil moisture should be monitored in the
field.

TOMATO IRRIGATION REQUIREMENT.
Irrigation systems are generally rated with respect to
application efficiency (Ea), which is the fraction of the water that
has been applied by the irrigation system and that is available to
the plant for use. In general, Ea is 20-70% for seepage irrigation
and 90-95% for drip irrigation. Applied water that is not available
to the plant may have been lost from the crop root zone through
evaporation or wind drifts of spray droplets, leaks in the pipe
system, surface runoff, subsurface runoff, or deep percolation
within the irrigated area. Tomato irrigation requirements are
determined by dividing the desired amount of water to provide to
the plant (ETc), by Ea as a decimal fraction (Eq. [2]).

In areas where real-time weather information is not
available, growers use the '1,000 gal/acre/day/string' rule for drip-
irrigated, winter production. As the tomato plants grow from 1 to
4 strings, the daily irrigation volumes increase from 1,000 gal/
acre/day to 4,000 gal/acre/day. On 6-ft centers, this corresponds
to 15 gal/1001bf/ day and 60 gal/1001bf/day for 1 and 4 strings,
respectively.

SOIL MOISTURE MEASUREMENT
Soil water tension (SWT) represents the magnitude of the
suction (negative pressure) the plant roots have to create to free
soil water from the attraction of the soil particles, and move it into
root cells. The dryer the soil, the higher the suction needed, hence,
the higher SWT. SWT is commonly expressed in centibars (cb) or
kiloPascals (kPa; Icb = IkPa). For tomatoes grown on the sandy
soils of Florida, SWT in the rooting zone should be maintained
between 6 (field capacity) and 15 cb.
The two most common tools available to measure SWT in
the field are tensiometers and time domain reflectometry (TDR)

-35-

probes. Tensiometers have been used for several years in tomato
production. A porous cup is saturated with water, and placed under
vacuum. As the soil water content changes, water comes in or out
of the porous cup, and affects the amount of vacuum inside the
tensiometer. Tensiometer readings have been successfully used
to monitor SWT and schedule irrigation for tomatoes. However,
because they are fragile and easily broken by field equipment,
many growers do not use them. In addition, readings are not
reliable when the tensiometer dries, or when the contact between
the cup and the soil is lost. Depending on the length of the access
tube, tensiometers cost between $40 and $80 each. Tensiometers
can be reused as long as they are maintained properly and remain
undamaged.
It is necessary to monitor SWT at two soil depths when
tensiometers are used. A shallow 6-in depth is useful at the
beginning of the season when tomato roots are near that depth.
A deeper 12-in depth is used to monitor SWT during the rest of
the season. Comparing SWT at both depth is useful to understand
the dynamics of soil moisture. When both SWT are within the
4-8 cb range (close to field capacity), this means that moisture is
plentiful in the rooting zone. This may happen after a large rain,
or when tomato water use is less than irrigation applied. When the
6-in SWT increases (from 4-8 cb to 10-15cb) while SWT at 12-in
remains within 4-8, the upper part of the soil is drying, and it is
time to irrigate. If the 6-in SWT continues to raise (above 25cb), a
water stress will result; plants will wilt, and yields will be reduced.
This should not happen under adequate water management.
A SWT at the 6-in depth remaining within the 4-8 cb range,
but the 12-in reading showing a SWT of 20-25 cb suggest that
deficit irrigation has been made: irrigation has been applied to re-
wet the upper part of the profile only. The amount of water applied
was not enough to wet the entire profile. If SWT at the 12-in depth
continues to increase, then water stress will become more severe
and it will become increasingly difficult to re-wet the soil profile.
The sandy soils of Florida have a low water holding capacity.
Therefore, SWT should be monitored daily and irrigation applied
at least once daily. Scheduling irrigation with SWT only can be
difficult at times. Therefore, SWT data should be used together
with an estimate of tomato water requirement
Times domain reflectometry (TDR) is not a new method
for measuring soil moisture but its use in vegetable production
has been limited in the past. The recent availability of inexpensive
equipment ($400 to $550/unit) has increased the potential of this
method to become practical for tomato growers. A TDR unit is
comprised of three parts: a display unit, a sensor, and two rods.
Rods may be 4 inches or 8 inches in length based on the depth of
the soil. Long rods may be used in all the sandy soils of Florida,
while the short rods may be used with the shallow soils of Miami-
Dade county.
The advantage of TDR is that probes need not be buried
permanently, and readings are available instantaneously. This
means that, unlike the tensiometer, TDR can be used as a hand-
held, portable tool.
TDR actually determines percent soil moisture (volume of
water per volume of soil). In theory, a soil water release curve
has to be used to convert soil moisture into SWT. However,
because TDR provides an average soil moisture reading over the

entire length of the rod (as opposed to the specific depth used for
tensiometers), it is not practical to simply convert SWT into soil
moisture to compare readings from both methods. Preliminary
tests with TDR probes have shown that best soil monitoring may
be achieved by placing the probe vertically, approximately 6
inches away from the drip tape on the opposite side of the tomato
plants. For fine sandy soils, 9% to 15% appears to be the adequate
moisture range. Tomato plants are exposed to water stress when
soil moisture is below 8%. Excessive irrigation may result in soil
moisture above 16%.

Guidelines for Splitting Irrigation. For sandy soils, a
one square foot vertical section of a 100-ft long raised bed can
hold approximately 24 to 30 gallons of water (Table 4). When
drip irrigation is used, lateral water movement seldom exceeds 6
to 8 inches on each side of the drip tape (12 to 16 inches wetted
width). When the volume of an irrigation exceeds the values in
table 4, then irrigation should be split. Splitting will not only
reduce nutrient leaching, it will also increase tomato quality by
ensuring a more continuous water supply. Uneven water supply
may result in fruit cracking.

Units for Measuring Irrigation Water. When overhead
and seepage irrigation were the dominant methods of irrigation,
acre-inches or vertical amounts of water were used as units for
irrigations recommendations. There are 27,150 gallons in one
acre-inch; thus, total volume was calculated by multiplying the
recommendation expressed in acre-inch by 27,150. This unit
reflected quite well the fact that the entire field was wetted.
Acre-inches are still used for drip irrigation, although the
entire field is not wetted. This section is intended to clarify the
conventions used in measuring water amounts for drip irrigation.
In short, water amounts are handled similarly to fertilizer amounts,
i.e., on an acre basis. When an irrigation amount expressed in
acre-inch is recommended for plasticulture, it means that the
recommended volume of water needs to be delivered to the row
length present in a one-acre field planted at the standard bed
spacing. So in this case, it is necessary to know the bed spacing
to determine the exact amount of water to apply. In addition, drip
tape flow rates are reported in gallons/hour/emitter or in gallons/
hour/i 00 ft of row. Consequently, tomato growers tend to think in
terms of multiples of 100 linear feet of bed, and ultimately convert
irrigation amounts into duration of irrigation. It is important to
correctly understand the units of the irrigation recommendation in
order to implement it correctly.

Example. How long does an irrigation event need to last if
a tomato grower needs to apply 0.20 acre-inch to a 2-acre tomato
field. Rows are on 6-ft centers and a 12-ft spray alley is left
unplanted every six rows? The drip tape flow rate is 0.30 gallons/
hour/emitter and emitters are spaced 1 foot apart.
1. In the 2-acre field, there are 14,520 feet of bed (2 x
43,560/6). Because of the alleys, only 6/8 of the field is
actually planted. So, the field actually contains 10,890
feet of bed (14,520x 6/8).

-36-

2. A 0.20 acre-inch irrigation corresponds to 5,430 gallons
applied to 7,260 feet of row, which is equivalent to
75gallons/100feet (5,430/72.6).

3. The drip tape flow rate is 0.30 gallons/hr/emitter which is
equivalent to 30 gallons/hr/100feet. It will take 1 hour to
apply 30 gallons/100ft, 2 hours to apply 60gallons/100ft,
and 2 12 hours to apply 75 gallons. The total volume
applied will be 8,168 gallons/2-acre (75 x 108.9).

Fertilizerandnutrientmanagementare essential components
of successful commercial tomato production. This article presents
the basics of nutrient management for the different production
systems used for tomato in Florida.

CALIBRATED SOIL TEST: TAKING THE
GUESSWORK OUT OF FERTILIZATION
Prior to each cropping season, soil tests should be conducted
to determine fertilizer needs and eventual pH adjustments. Obtain
a UF/IFAS soil sample kit from the local agricultural Extension
agent for this purpose. If a commercial soil testing laboratory is
used, be sure the lab uses methodologies calibrated and extractants
suitable for Florida soils. When used with the percent sufficiency
philosophy, routine soil testing helps adjust fertilizer applications
to plant needs and target yields. In addition, the use of routine
calibrated soil tests reduces the risk of over-fertilization. Over
fertilization reduces fertilizer efficiency and increases the risk of
groundwater pollution. Systematic use of fertilizer without a soil
test may also result in crop damage from salt injury.
The crop nutrient requirements of nitrogen, phosphorus,
and potassium (designated in fertilizers as N-P20,-K20) represent
the optimum amounts of these nutrients needed for maximum
tomato production (Table 1). Fertilizer rates are provided on a
per-acre basis for tomato produced on 6-ft centers. Under these
conditions, there are 7,260 linear feet of tomato row in an acre.
When different row spacings are used or when a significant
number of drive rows are left unplanted, it is necessary to adjust
fertilizer application accordingly.
Fertilizer rates can be simply and accurately adjusted
to row spacings other than the standard spacing (6-ft centers)
by expressing the recommended rates on a 100 linear bed feet
(Ibf) basis, rather than on a real-estate acre basis. For example,
in a 1-acre tomato field planted on 7-ft centers with one drive
row every six rows, there are only 5,333 lbf (6/7 x 43,560 / 7).
If the recommendation is to inject 10 lbs of N per acre (standard
spacing), this becomes 10 lbs ofN/7,260 lbf or 0.141bs N/100 lbf.
Since there are 5,333 lbf/acre in this example, then the adjusted
rate for this situation is 7.46 lbs N/acre (0.14 x 53.33). In other
words, an injection of 10 lbs of N to 7,260 lbf is accomplished by
injecting 7.46 lbs ofN to 5,333 lbf.

LIMING
The optimum pH range for tomatoes is 6.0 and 6.5. This is
the range for which the availability of all the essential nutrients
is highest. Fusarium wilt problems are reduced by liming within
this range, but it is not advisable to raise the pH above 6.5
because of reduced micronutrient availability. In areas where soil

pH is basic (>7.0), micronutrient deficiencies may be corrected
by foliar sprays.
Calcium and magnesium levels should be corrected
according to the soil test. If both elements are "low", and lime
is needed, then broadcast and incorporate dolomitic limestone.
Where calcium alone is deficient, lime with "hi-cal" limestone.
Adequate calcium is important for reducing the severity of
blossom-end rot. Research shows that a Mehlich-I (double-acid)
index of 300 to 350 ppm Ca would be indicative of adequate soil-
Ca. On limestone soils, add 30-40 pounds per acre of magnesium
in the basic fertilizer mix. It is best to apply lime several months
prior to planting. However, if time is short, it is better to apply
lime any time before planting than not to apply it at all. Where
the pH does not need modification, but magnesium is low, apply
magnesium sulfate or potassium-magnesium sulfate with the
fertilizer.
Changes in soil pH may take several weeks to occur when
carbonate-based liming materials are used (calcitic or dolomitic
limestone). Oxide-based liming materials (quick lime -CaO- or
dolomitic quick lime -CaO, MgO-) are fast reacting and rapidly
increase soil pH. Yet, despite these advantages, oxide-based
lime is more expensive than the traditional liming materials, and
therefore are not routinely used.
The increase in pH induced by liming materials is NOT
due to the presence of calcium or magnesium. Instead, it is the
carbonate ("CO3") and oxide ("O") part of CaCO3 and 'CaO',
respectively, that raises the pH. Through several chemical
reactions that occur in the soil, carbonates and oxides release OH-
ions that combine with HI to produce water. As large amounts of
HI react, the pH rises. A large fraction of the Ca and/or Mg in the
liming materials gets into solution and binds to the sites that are
freed by HI that have reacted with OH-.

FERTILIZER-RELATED PHYSIOLOGICAL
DISORDERS
Blossom-End Rot. Growers may have problems with
blossom-end-rot, especially on the first or second fruit clusters.
Blossom-end rot (BER) is a Ca deficiency in the fruit, but is often
more related to plant water stress than to Ca concentrations in the
soil. This is because Ca movement in the plant occurs with the
water (transpiration) stream. Thus, Ca moves preferentially to the
leaves. As a maturing fruit is not a transpiring organ, most of the
Ca is deposited during early fruit growth.
Once BER symptoms develop on a tomato fruit, they
cannot be alleviated on this fruit. Because of the physiological
role of Ca in the middle lamella of cell walls, BER is a structural
and irreversible disorder. Yet, the Ca nutrition of the plant can
be altered so that the new fruits are not affected. BER is most
effectively controlled by attention to irrigation and fertilization,
or by using a calcium source such as calcium nitrate when soil Ca
is low. Maintaining adequate and uniform amounts of moisture in
the soil are also keys to reducing BER potential.
Factors that impair the ability of tomato plants to obtain
water will increase the risk of BER. These factors include
damaged roots from flooding, mechanical damage or nematodes,
clogged drip emitters, inadequate water applications, alternating
dry-wet periods, and even prolonged overcast periods. Other

-39-

causes for BER include high fertilizer rates, especially potassium
and nitrogen. High total fertilizer increases the salt content and
osmotic potential in the soil reducing the ability of roots to obtain
water, and high N increases leaf and shoot growth to which Ca
preferentially moves, by-passing fruits.
Calcium levels in the soil should be adequate when the
Mehlich-1 index is 300 to 350 ppm, or above. In these cases, added
gypsum (calcium sulfate) is unlikely to reduce BER. Foliar sprays
of Ca are unlikely to reduce BER because Ca does not move out of
the leaves to the fruit.

Gray Wall. Blotchy ripening (also called gray wall) of
tomatoes is characterized by white or yellow blotches that appear
on the surface of ripening tomato fruits, while the tissue inside
remains hard. The affected area is usually on the upper portion
of the fruit. The etiology of this disorder has not been formally
established, but it is often associated with high N and/or low K,
and aggravated by excessive amount of N. This disorder may
be at times confused with symptoms produced by the tobacco
mosaic virus. Gray wall is cultivar specific and appears more
frequently on older cultivars. The incidence of gray wall is less
with drip irrigation where small amounts of nutrients are injected
frequently, than with systems where all the fertilizer is applied
pre-plant.

Micronutrients. For virgin, acidic sandy soils, or sandy
soils where a proven need exists, a general guide for fertilization
is the addition of micronutrients (in elemental lbs/A) manganese
-3, copper -2, iron -5, zinc -2, boron -2, and molybdenum -0.02.
Micronutrients may be supplied from oxides or sulfates. Growers
using micronutrient-containing fungicides need to consider these
sources when calculating fertilizer micronutrient needs. More
information on micronutrient use is available from the suggested
literature list.
Properly diagnosed micronutrient deficiencies can often be
corrected by foliar applications of the specific micronutrient. For
most micronutrients, a very fine line exists between sufficiency
and toxicity. Foliar application of major nutrients (nitrogen,
phosphorus, or potassium) has not been shown to be beneficial
where proper soil fertility is present.

FERTILIZER APPLICATION
Mulch Production with Seepage Irrigation. Under this
system, the crop may be supplied with all of its soil requirements
before the mulch is applied (Table 1). It is difficult to correct
a deficiency after mulch application, although a liquid fertilizer
injection wheel can facilitate sidedressing through the mulch.
The injection wheel will also be useful for replacing fertilizer
under the used plastic mulch for double-cropping systems. A
general sequence of operations for the full-bed plastic mulch
system is:
1. Land preparation, including development of irrigation
and drainage systems, and liming of the soil, if needed.

2. Application of "starter" fertilizer or "in-bed" mix. This
should comprise only 10 to 20 percent of the total nitrogen
and potassium seasonal requirements and all of the

needed phosphorus and micronutrients. Starter fertilizer
can be broadcast over the entire area prior to bedding
and then incorporated. During bedding, the fertilizer
will be gathered into the bed area. An alternative is to
use a "modified broadcast" technique for systems with
wide bed spacings. Use of modified broadcast or banding
techniques can increase phosphorus and micronutrient
efficiencies, especially on alkaline (basic) soils.

3. Formation of beds, incorporation of herbicide, and
application of mole cricket bait.

4. Application of remaining fertilizer. The remaining 80
to 90 percent of the nitrogen and potassium is placed in
narrow bands 9 to 10 inches to each side of the plant
row in furrows. The fertilizer should be placed deep
enough in the grooves for it to be in contact with moist
bed soil. Bed presses are modified to provide the groove.
Only water-soluble nutrient sources should be used for
the banded fertilizer. A mixture of potassium nitrate (or
potassium sulfate or potassium chloride), calcium nitrate,
and ammonium nitrate has proven successful.

5. Fumigation, pressing of beds, and mulching. This
should be done in one operation, if possible. Be sure
that the mulching machine seals the edges of the mulch
adequately with soil to prevent fumigant escape.

Water management with the seep irrigation system is
critical to successful crops. Use water-table monitoring devices
and/or tensiometers in the root zone to help provide an adequate
water table but no higher than required for optimum moisture. It is
recommended to limit fluctuations in water table depth since this
can lead to increased leaching losses of plant nutrients.

Mulched Production with Drip Irrigation. Where drip
irrigation is used, drip tape or tubes should be laid 1 to 2 inches
below the bed soil surface prior to mulching. This placement helps
protect tubes from mice and cricket damage. The drip system is an
excellent tool with which to fertilize tomato. Where drip irrigation
is used, apply all phosphorus and micronutrients, and 20 percent
to 40 percent of total nitrogen and potassium preplant, prior to
mulching. Apply the remaining nitrogen and potassium through
the drip system in increments as the crop develops.
Successful crops have resulted where the total amounts of
N and K20 were applied through the drip system. Some growers
find this method helpful where they have had problems with
soluble-salt burn. This approach would be most likely to work
on soils with relatively high organic matter and some residual
potassium. However, it is important to begin with rather high
rates of N and K20 to ensure young transplants are established
quickly. In most situations, some preplant N and K fertilizers are
needed.
Suggested schedules for nutrient injections have been
successful in both research and commercial situations, but might
need slight modifications based on potassium soil-test indices and
grower experience (Table 1).

-40-

SOURCES OF N-P20-K0.
About 30 to 50 percent of the total applied nitrogen should
be in the nitrate form for soil treated with multi-purpose fumigants
and for plantings in cool soil.
Controlled-release nitrogen sources may be used to
supply a portion of the nitrogen requirement. One-third of the
total required nitrogen can be supplied from sulfur-coated urea
(SCU), isobutylidene diurea (IBDU), or polymer-coated urea
(PCU) fertilizers incorporated in the bed. Nitrogen from natural
organic and most controlled-release materials is initially in the
ammoniacal form, but is rapidly converted into nitrate by soil
microorganisms.
Normal superphosphate and triple superphosphate are
recommended for phosphorus needs. Both contribute calcium and
normal superphosphate contributes sulfur.
All sources of potassium can be used for tomatoes.
Potassium sulfate, sodium-potassium nitrate, potassium nitrate,
potassium chloride, monopotassium phosphate, and potassium-
magnesium sulfate are all good K sources. If the soil test predicted
amounts of KO2 are applied, then there should be no concern for
the K source or its associated salt index.

SAP TESTING AND TISSUE ANALYSIS
While routine soil testing is essential in designing a
fertilizer program, sap tests and/or tissue analyses reveal the actual
nutritional status of the plant. Therefore these tools complement
each other, rather than replace one another.
Analysis of tomato leaves for mineral nutrient content can
help guide a fertilizer management program during the growing
season or assist in diagnosis of a suspected nutrient deficiency.
Tissue nutrient norms are presented in Table 2. Growers with
drip irrigation can obtain faster analyses for N or K by using a
plant sap quick test. Several kits have been calibrated for Florida
tomatoes (Table 3).
For both nutrient monitoring tools, the quality and reliability
of the measurements are directly related with the quality of the
sample. A leaf sample should contain at least 20 most recently,
fully developed, healthy leaves. Select representative plants, from
representative areas in the field.

SUPPLEMENTAL FERTILIZER APPLICATIONS
In practice, supplemental fertilizer applications allow
vegetable growers to numerically apply fertilizer rates higher
than the standard UF/IFAS recommended rates when growing
conditions require to do so. The two main growing conditions that
may require supplemental fertilizer applications are leaching rains
and extended harvest periods. Applying additional fertilizer under
the three circumstances described in Table 1 is part of the current
UF/IFAS fertilizer recommendations and nutrient BMPs.

Levels of Nutrient Management for Tomato Production
Based on the growing situation and the level of adoption
of the tools and techniques described above, different levels of
nutrient management exist for tomato production in Florida.
Successful production requires management levels of 3 or above
(Table 4).

z1 A = 7,260 linear bed feet per acre (6-ft bed spacing); for soils testing 'very low' in Mehlich 1 potassium (K20).
Y applied using the modified broadcast method (fertilizer is broadcast where the beds will be formed only, and not over the entire field).
Preplant fertilizer cannot be applied to double/triple crops because of the plastic mulch; hence, in these cases, all the fertilizer has to be
injected.
x This fertigation schedule is applicable when no N and K20 are applied preplant. Reduce schedule proportionally to the amount of N and
K20 applied preplant. Fertilizer injections may be done daily or weekly. Inject fertilizer at the end of the irrigation event and allow enough
time for proper flushing afterwards.
w For a standard 13 week-long, transplanted tomato crop grown in the Spring.
Some of the fertilizer may be applied with a fertilizer wheel though the plastic mulch during the tomato crop when only part of the
recommended base rate is applied preplant. Rate may be reduced when a controlled-release fertilizer source is used.
Plant nutritional status may be determined with tissue analysis or fresh petiole-sap testing, or any other calibrated method. The 'low'
diagnosis needs to be based on UF/IFAS interpretative thresholds.
SPlant nutritional status must be diagnosed every week to repeat supplemental application.
s Supplemental fertilizer applications are allowed when irrigation is scheduled following a recommended method. Supplemental fertilization
is to be applied in addition to base fertilization when appropriate. Supplemental fertilization is not to be applied 'in advance' with the
preplant fertilizer.
rA leaching rain is defined as a rainfall amount of 3 inches in 3 days or 4 inches in 7 days.
q Supplemental amount for each leaching rain
P Plant nutritional status must be diagnosed after each harvest before repeating supplemental fertilizer application.

Limit is 3 appl./crop, see label
Limit is 3 appl./crop. Tank
mix with maneb or mancozeb
fungicide, see label

See label for restrictions and
use (e.g. use of 400 psi spray
pressure)
Using potassium carbonate
or Diammonium phosphate,
the spray of Aliette should be
raised to a pH of 6.0 or above
when applied prior to or after
copper fungicides, see label
Use higher rates at fruit set,
see label

Use higher rates at fruit set,
see label

4 Ibs.

10 Botrytis

3 4 ozs. 1.25 Ibs. 0 Powdery mildew

Greenhouse use only. Limit
is 4 applications. Seedlings or
newly set transplants may be
injured, see label
Note that a 30 day plant back
restriction exists, see label

Only in a tank mixture with
chlorotalonil, maneb or
mancozeb, see label

Do not use alone, see label for
details
See label for details

See label for details
Dosage given is for drip
application.
See label for restrictions and
details
Use only in a tank mix with
another effective fungicide
(non FRAC code 9), see label
Alternate with non-FRAC code
7 fungicides, see label
See label for application type
and restrictions

Remarks2
Mancozeb or maneb enhances
bactericidal effect of fix copper
compounds, see label
Mancozeb or maneb enhances
bactericidal effect of fix copper
compounds, see label
Mancozeb or maneb enhances
bactericidal effect of fix copper
compounds, see label
Mancozeb or maneb enhances
bactericidal effect of fix copper
compounds, see label
Mancozeb or maneb enhances
bactericidal effect of fix copper
compounds, see label
Greenhouse use only. Allow
can to remain overnight and
then ventilate. Do not use
when greenhouse temperature
is above 75 F, see label

FRAC code (fungicide group): Numbers (1-37) and letters (M, U, P) are used to distinguish the fungicide mode of action groups.
All fungicides within the same group (with same number or letter) indicate same active ingredient or similar mode of action. This
information must be considered for the fungicide resistance management decisions. M = Multi site inhibitors, fungicide resistance risk
is low; U = Recent molecules with unknown mode of action; P = host plant defense inducers. Source: http://www.frac.info/ (FRAC =
Fungicide Resistance Action Committee)
2 Information provided in this table applies only to Florida. Be sure to read a current product label before applying any chemical. The use
of brand names and any mention or listing of commercial products or services in the publication does not imply endorsement by the
University of Florida Cooperative Extension Service nor discrimination against similar products or services not mentioned.
3Tank mix of mancozeb or maneb enhances bactericidal effect of copper compounds.

2 One application per
season.
4A Most effective if
applied to soil at
transplanting. Limited
to 24 oz/acre.
4A Greenhouse Use: 1
application to mature
plants, see label for
cautions.

4A Planthouse: 1
application. See label.

11B1 Apply when larvae
are small for best
control. Can be used
in greenhouse. OMRI-
listed2.
6 Do not make more
than 2 sequential
applications. Do not
apply more than 48 fl
oz per acre per season.
3 Do not use on cherry
tomatoes. Do not
apply more than
1.2 Ib ai/acre per
season (76.8 oz). Not
recommended for
control of vegetable
leafminer in Florida.
3 Not recommended for
control of vegetable
leafminer in Florida.
Do not apply more
than 0.5 Ib ai per acre
per season, or 10
applications at highest
rate.

4A Do not apply to
crop that has been
already treated
with imidacloprid
or thiamethoxam
at planting. Begin
applications for
whiteflies when first
adults are noticed. Do
not apply more than
4 times per season or
apply more often than
every 7 days.
22 Do not apply more
than 14 ounces of
product per acre per
crop. Minimum spray
interval is 5 days.
26 Antifeedant, repellant,
insect growth
regulator. OMRI-listed2.

26 Antifeedant, repellant,
insect growth
regulator.

3 (1) Ist and 2nd instars
only

(2) suppression
Do not apply more than
0.26 Ib ai per acre per
season.

Maximum number of
applications: 6.
11B2 Treat when larvae
are young. Good
coverage is essential.
Can be used in the
greenhouse.
OMRI-listed2.
May be used in
greenhouses.
Contact dealer for
recommendations if an
adjuvant must be used.
Not compatible in tank
mix with fungicides.
3 Make no more than
4 applications per
season. Do not make
applications less than
10 days apart.

For mating disruption -
See label.
TPW formulation.
OMRI-listed2.
11B2 Do not use in
combination with any
chlorothalonil-based
fungicides. Use caution
when mixing with other
oil-based products or
surfactants. Treat when
larvae are young. Good
coverage is essential.
18 Product is a
slow-acting IGR that
will not kill larvae
immediately. Do not
apply more than 1.0 Ib
ai per acre per season.
16 See label for plantback
restrictions. Apply
when a threshold is
reached of 5 nymphs
per 10 leaflets from
the middle of the
plant. Product is a
slow-acting IGR that
will not kill nymphs
immediately. No more
than 2 applications
per season. Allow at
least 28 days between
applications.
11B2 Use high rate for
armyworms. Treat
when larvae are young.

3 Use alone for control
of fruitworms, stink
bugs, twospotted
spider mites, and
yellowstriped
armyworms. Tank-mix
with Monitor 4 for
all others, especially
whitefly. Do not apply
more than 0.8 Ib ai
per acre per season.
Do not tank mix with
copper.
11B2 Use higher rates for
armyworms. OMRI-
listed2.

1B Will not control
organophosphate-
resistant leafminers.
Do not apply more than
five times per season.

1B Will not control
organophosphate-
resistant leafminers.

11B2 Treat when larvae are
young. Good coverage
is essential. OMRI-
listed2.
2 Do not exceed a
maximum of 3.0 Ib
active ingredient per
acre per year or apply
more than 6 times. Can
be used in greenhouse.
5 Do not apply more than
9 oz per acre per crop.
OMRI-listed2.

7C Apply when ants are
actively foraging.
7A Slow-acting IGR (insect
growth regulator). Best
applied early spring
and fall where crop will
be grown. Colonies will
be reduced after three
weeks and eliminated
after 8 to 10 weeks.
May be applied by
ground equipment or
aerially.
9B Do not make more
than four applications.
24(c) label for growing
transplants also.

18 Do not apply more
than 64 fl oz acre per
season.
Product is a slow-
acting IGR that will not
kill larvae immediately.

11B2 Treat when larvae
are young. Thorough
coverage is essential.
OMRI-listed2.
20 Do not apply more than
twice a season or more
than 1.6 pts per year.

7C Apply when a threshold
is reached of 5 nymphs
per 10 leaflets from
the middle of the
plant. Product is a
slow-acting IGR that
will not kill nymphs
immediately. Make
no more than two
applications per
season.
9A Minimum of 7 days
between applications.
Do not apply more than
64 Ibs per acre per
season. Not for cherry
tomatoes.
1A Do not apply more than
6.3 Ib ai/acre per crop.

11B2 Treat when larvae
are small. Thorough
coverage is essential.

1B Can be used in
greenhouse.

1B (1) Use as tank mix
with a pyrethroid for
whitefly control.
Do not apply more than
10 pts per acre, or 18
pts per acre in North
Florida per season.
OMRI-listed2.

9A Minimum of 7 days
between applications.
Do not apply more than
64 Ibs per acre per
season. Not for cherry
tomatoes.
4A Do not apply to
crop that has been
already treated with
imidacloprid or
thiamethoxam at
planting. Do not apply
more than 18.75 oz per
acre as foliar spray.

1A (1) suppression

Do not apply more than
seven times. Do not
apply a total of more
than 10 lb or 8 qt per
acre per crop.

5 Do not apply to
seedlings grown for
transplant within
a greenhouse or
shadehouse. Leafminer
and thrips control may
be improved by adding
an adjuvant. Do not
apply more than three
times in any 21 day
period. Do not apply
more than 29 ozs per
acre per crop.

See supplemental
label for restrictions
in certain Florida
counties.
17 No more than 6
applications per crop.
26 Apply morning or
evening to reduce
potential for leaf burn.
Toxic to bees exposed
to direct treatment.
OMRI-listed2.
Do not exceed four
applications per
season. Organic Stylet-
Oil is
OMRI-listed2.
4A Use only one
application method
(soil or foliar) do not
apply more than 1.34
Ib/acre (foliar) or 2.68
Ib/acre (soil) per crop
season.
1A Do not apply more than
32 pts per acre per
season.

3 (1) suppression only
(2) for control of 1st and
2nd instars only.
Do not apply more than
0.36 Ib ai per acre per
season.
(')Does not control
western flower thrips.

-56-

Days
Trade Name Rate REI to MOA
(Common Name) (product/acre) (hours) Harvest Insects Code1 Notes
Xentari DF 0.5-2 Ib 4 0 caterpillars 11B1 Treat when larvae
(Bacillus are young. Thorough
thuringiensis coverage is essential.
subspecies aizawai) May be used in the
greenhouse. Can
be used in organic
production. OMRI-
listed2.

The following table lists many of the common insecticides
currently labeled for use on vegetables in Florida. A number
of new materials have been registered in the past few years or
have had additional crops added to their labels. Some older
organophosphate insecticides (methyl parathion, in particular) are
now restricted to just a few crops, a result of recent rulings related
to the Food Quality Protection Act. Changes continue, thus this
listing may not be totally accurate at the time of printing.

No attempt has been made to list all available formulations.
Some are listed under "Signal Word," when different formulations
differ in toxicity. Many of the listed insecticides are limited to
specific vegetables. Specific crop recommendations and pesticide
labels should be consulted for more detailed information.

Insects can become resistant to any insecticide if it is
used repeatedly. This also applies to alternating insecticides with
similar modes of action, for example following a soil application
of Admire with foliar applications of Actara or Assail (all
neonicotinoids). To complicate matters, some insecticides in the
same class have different modes of action and some unrelated
chemicals have the same mode of action. In general, pesticides
with the same mode of action s should be used no more than twice
in any crop cycle if residual activity is short and only once if
residual activity is long. To aid in developing a spray program we
have included a column with a code number for the mode of action
of each insecticide. A footnote lists the mode of action associated
with the code. In addition to alternating insecticides with different
modes of action, integrating other non-chemical control measures
in a pest management program should help to delay resistance.

1 This document is ENY-419, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service,
Institute of Food and Agricultural Sciences, University of Florida. Revised: July 2005. Please visit the EDIS Website at http://edis.ifas.
ufl.edu.
2 S.E. Webb, associate professor/extension entomologist, Entomology and Nematology Department, Cooperative Extension Service,
Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611, and P. A. Stansly, professor, Entomology and
Nematology Department, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, 34142.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or
warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products
of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label. Use pesticides safely.
Read and follow directions on the manufacturer's label.

slow acting
use in combination or rotation
with other insecticides
slow acting, also acts as
feeding repellent

disrupts cuticle formation
and deposition at molting,
resulting in death of larva; no
effect on adult insect
most effective against small
leafminer larvae

local systemic

systemic, long residual

local systemic, ovicidal effects

systemic, long residual

local systemic

systemic or locally systemic,
depending on application
method, long residual

pest must ingest; slow acting
but feeding stops long before
death
pest must ingest; slow acting
but feeding stops long before
death
pest must ingest; not
rainfast; an inorganic fluorine
compound
contact; slow acting

inhibitor of lipid synthesis;
most effective on juvenile
stages of mites and on
nymphs and pupae of
whiteflies and psyllids

Although weed control has always been an important
component of tomato production, its importance has increased
with the introduction of the sweet potato whitefly and development
of the associated irregular ripening problem. Increased incidence
of several viral disorders of tomatoes also reinforces the need
for good weed control. Common weeds, such as the difficult to
control nightshade, and volunteer tomatoes (considered a weed
in this context) are hosts to many tomato pests, including sweet
potato whitefly, bacterial spot, and viruses. Control of these pests
is often tied, at least in part, to control of weed hosts. Most growers
concentrate on weed control in row middles; however, peripheral
areas of the farm may be neglected. Weed hosts and pests may
flourish in these areas and serve as reservoirs for re-infestation
of tomatoes by various pests. Thus, it is important for growers to
think in terms of weed management on all of the farm, not just the
actual crop area.
Total farm weed management is more complex than row
middle weed control because several different sites, and possible
herbicide label restrictions are involved. Often weed species in
row middles differ from those on the rest of the farm, and this
might dictate different approaches. Sites other than row middles
include roadways, fallow fields, equipment parking areas, well
and pump areas, fence rows and associated perimeter areas, and
ditches.
Disking is probably the least expensive weed control
procedure for fallow fields. Where weed growth is mostly grasses,
clean cultivation is not as important as in fields infested with
nightshade and other disease and insect hosts. In the latter situation,
weed growth should be kept to a minimum throughout the year. If
cover crops are planted, they should be plants which do not serve
as hosts for tomato diseases and insects. Some perimeter areas are
easily disked, but berms and field ditches are not and some form
of chemical weed control may have to be used on these areas.
We are not advocating bare ground on the farm as this can lead
to other serious problems, such as soil erosion and sand blasting
of plants; however, where undesirable plants exist, some control
should be practiced, if practical, and replacement of undesirable
species with less troublesome ones, such as bahiagrass, might be
worthwhile.
Certainly fence rows and areas around buildings and
pumps should be kept weed-free, if for no other reason than
safety. Herbicides can be applied in these situations, provided care
is exercised to keep it from drifting onto the tomato crop. Field
ditches as well as canals are a special consideration because many
herbicides are not labeled for use on aquatic sites. Where herbicidal
spray may contact water and be in close proximity to tomato
plants, for all practical purposes, growers probably would be wise
to use Diquat only. On canals where drift onto the crop is not a
problem and weeds are more woody, Rodeo, a systemic herbicide,

could be used. Other herbicide possibilities exist, as listed in Table
1. Growers are cautioned against using Arsenal on tomato farms
as tomatoes are very sensitive to this herbicide. Particular caution
should be exercised if Arsenal is used on seepage irrigated farms
as it has been observed to move in some situations.

Use of rye as a windbreak has become a common practice in
the spring; however, in some cases, adverse effects have resulted.
If undesirable insects such as thrips buildup on the rye, contact
herbicide can be applied to kill it and eliminate it as a host, yet the
remaining stubble could continue serving as a windbreak.
The greatest row middle weed control problem confronting
the tomato industry today is control of nightshade. Nightshade
has developed varying levels of resistance to some post-emergent
herbicides in different areas of the state. Best control with post-
emergence (directed) contact herbicides are obtained when the
nightshade is 4 to 6 inches tall, rapidly growing and not stressed.
Two applications in about 50 gallons per acre using a good
surfactant is usually necessary.
With post-directed contact herbicides, several studies have
shown that gallonage above 60 gallons per acre will actually dilute
the herbicides and therefore reduce efficacy. Good leaf coverage
can be obtained with volumes of 50 gallons or less per acre. A
good surfactant can do more to improve the wetting capability
of a spray than can increasing the water volume. Many adjuvants
are available commercially. Some adjuvants contain more active
ingredient then others and herbicide labels may specify a minimum
active ingredient rate for the adjuvant in the spray mix. Before
selecting an adjuvant, refer to the herbicide label to determine the
adjuvant specifications.

POSTHARVEST VINE DESSICATION
Additionally important is good field sanitation with regard
to crop residue. Rapid and thorough destruction of tomato vines
at the end of the season always has been promoted; however, this
practice takes on new importance with the sweet potato whitefly.
Good canopy penetration of pesticidal sprays is difficult with
conventional hydraulic sprayers once the tomato plant develops
a vigorous bush due to foliar interception of spray droplets.
The sweet potato whitefly population on commercial farms was
observed to begin a dramatic, rapid increase about the time of first
harvest in the spring of 1989. This increase appears to continue
until tomato vines are killed. It is believed this increase is due,
in part, to coverage and penetration. Thus, it would be wise
for growers to continue spraying for whiteflies until the crop is
destroyed and to destroy the crop as soon as possible with the
fastest means available. Both diquat and paraquat are now labeled
for postharvest dessication of tomato vines. The labels differ
slightly so it's important to follow the label directions.
The importance of rapid vine destruction can not be
overstressed. Merely turning off the irrigation and allowing the
crop to die is not sufficient; application of a desiccant followed by
burning is the prudent course.

-63-

Herbicide Labeled Crops Time of Application Rate (Ibs. Al./Acre)
to Crop Mineral Muck
Carfentrazone Fruiting Vegetables Directed-hooded 0.08-05 08-
0.008-0.025 0.008-0.025
(Aim) Tomato row-middles
Remarks: Aim may be applied as a post-directed hooded burn-down application to emerged broadleaf weeds in row
middles. Aim is not labeled for grassy weeds. May be tank mixed with other herbicides registered for this treatment
pattern. May be applied at 0.33 oz (0.008 Ib ai) to 1 oz (0.025 Ib ai). Use a quality spray adjuvant such as crop oil
concentrate (coc) or non-ionic surfactant (nis) at recommended rates.
Clethodim
SletE) Tomatoes Postemergence 0.9-.125 ---
(Select 2 EC)
Remarks: Postemergence control of actively growing annual grasses. Apply at 6-8 fl oz/acre. Use high rate under heavy
grass pressure and/or when grasses are at maximum height. Always use a crop oil concentrate at 1% v/v in the finished
spray volume. Do not apply within 20 days of tomato harvest.
DCPA pPosttransplanting after crop
Established Tomatoes establishment 6.0-8.0 ---
(Dacthal W-75) (non-mulched)
(non-mulched)
Remarks: Controls germinating annuals. Apply to weed-free soil 6 to 8 weeks after crop is established and growing rapidly
or to moist soil in row middles after crop establishment. Note label precautions of replanting non-registered crops within 8
months.
Diquat
Diquat Tomato Vine Burndown After final harvest 0.375 ---
(Reglone)
Remarks: Special Local Needs (24c) label for use for burndown of tomato vines after final harvest. Applications of 1.5 pts.
material per acre in 60 to 120 gals. of water is labeled. Add 16 to 32 oz. of Valent X-77 spreader per 100 gals. of spray
mix. Thorough coverage of vines is required to insure maximum burndown.
Pretransplant
Diquat dibromide
D t dromde Tomato Postemergence directed- 0.5 ---
(Reglshielded in row middles
Remarks: Diquat can be applied as a post-directed application to row middles either prior to transplanting or as a post-
directed hooded spray application to row middles when transplants are well established. Apply 1 qt of Diquat in 20-50
gallons of water per treated acre when weeds are 2-4 inches in height. Do not exceed 25 psi spray pressure. A maximum
of 2 applications can be made during the growing season. Add 2 pts non-ionic surfactant per 100 gals spray mix. Diquat
will be inactivated if muddy or dirty water is used in spray mix. A 30 day PHI is in effect. Label is a special local needs label
for Florida only.
Halo lfurn Pre-transplant
aosuuron Tomatoes Postemergtence 0.024 0.036 ---
(Sandea) Row middles
Remarks: A total of 2 applications of Sandea may be applied as either one pre-transplant soil surface treatment at 0.5-
0.75 oz. product; one over-the-top application 14 days after transplanting at 0.5-0.75 oz. product; and/or postemergence
applications(s) of up to 1 oz. product (0.047 Ib ai) to row middles. A 30-day PHI will be observed. For postemergence and
row middle applications, a surfactant should be added to the spray mix.
MCDS (Enquik) Tomatoes ergence directed/ 5 8 gals. ---
shielded in row middle
Remarks: Controls many emerged broadleaf weeds. Weak on grasses. Apply 5 to 8 gallons of Enquik in 20 to 50 gallons
of total spray volume per treated acre. A non-ionic surfactant should be added at 1 to 2 pints per 100 gallons. Enquik is
severely corrosive to nylon. Non-nylon plastic and 316-L stainless steel are recommended for application equipment. Read
the precautionary statements before use. Follow all restrictions on the label.
S-Metolachlor Pretransplant 1. .
Tomatoes 1.0 1.3 ---
(Dual Magnum) Row middles
Remarks: Apply Dual Magnum preplant non-incorporated to the top of a pressed bed as the last step prior to laying
plastic. May also be used to treat row-middles. Label rates are 1.0-1.33 pts/A if organic matter is less than 3%. Research
has shown that the 1.33 pt may be too high in some Florida soils except in row middles. Good results have been seen at
0.6 pts to 1.0 pints especially in tank mix situations under mulch. Use on a trial basis.

-64-

Herbicide Labeled Crops Time of Application Rate (Ibs. Al./Acre)
to Crop Mineral Muck
Metribuzin Postemergence
Snr STomatoes Posttransplanting after 0.25 0.5
(Sencor DF) (Sencor 4) establishment
establishment
Remarks: Controls small emerged weeds after transplants are established direct-seeded plants reach 5 to 6 true leaf stage.
Apply in single or multiple applications with a minimum of 14 days between treatments and a maximum of 1.0 Ib ai/acre
within a crop season. Avoid applications for 3 days following cool, wet or cloudy weather to reduce possible crop injury.
Metribuzin TmatDirected spray in row 05-1
Tomatoes 0.25 1.0 ---
(Sencor DF) (Sencor 4) middles
Remarks: Apply in single or multiple applications with a minimum of 14 days between treatments and maximum of 1.0
Ib ai/acre within crop season. Avoid applications for 3 days following cool, wet or cloudy weather to reduce possible
crop injury. Label states control of many annual grasses and broadleaf weeds including, lambsquarter, fall panicum,
amaranthus sp., Florida pusley, common ragweed, sicklepod, and spotted spurge.
Napropamid
(vrinol 5 ) Tomatoes Preplant incorporated 1.0 2.0 ---
(Devrinol 50DF)
Remarks: Apply to well worked soil that is dry enough to permit thorough incorporation to a depth of 1 to 2 inches.
Incorporate same day as applied. For direct-seeded or transplanted tomatoes.
Napropamid
DeNpropmid Tomatoes Surface treatment 2.0 ---
(Devrinol 50DF)
Remarks: Controls germinating annuals. Apply to bed tops after bedding but before plastic application. Rainfall or
overhead-irrigate sufficient to wet soil 1 inch in depth should follow treatment within 24 hours. May be applied to row
middles between mulched beds. A special Local Needs 24(c) Label for Florida. Label states control of weeds including
Texas panicum, pigweed, purslane, Florida pusley, and signalgrass.
Oxyfluorfen Tomatoes Fallow bed 0.25 0.5
(Goal 2XL)
Remarks: Must have a 30 day treatment-planting interval. Apply as a preemergence broadcast or banded treatment at 1-2
pt/A to preformed beds. Mulch may be applied any time during the 30-day interval.
Paraquat
(Gramoxone Extra) Tomatoes Premergence; Pretransplant 0.62 0.94 ---
(Gramoxone Max)
Remarks: Controls emerged weeds. Use a non-ionic spreader and thoroughly wet weed foliage.
Paraquat
Paraquat Post directed spray in row
(Gramoxone Extra) Tomatoes died 0.47 ---
(Gramoxone Max)
Remarks: Controls emerged weeds. Direct spray over emerged weeds 1 to 6 inches tall in row middles between mulched
beds. Use a non-ionic spreader. Use low pressure and shields to control drift. Do not apply more than 3 times per season.
Paraquat
Paraquat Postharvest
(Gramoxone Extra) Tomato dessication 0.62-0.93 0.46-0.62
(Gramoxone Extra)
Remarks: Broadcast spry over the top of plants after last harvest. Label for Boa states use of 1.5-2.0 pts while Gramoxone
label is from 2-3 pts. Use a nonionic surfactant at 1 pt/100 gals to 1 qt/100 gals spray solution. Thorough coverage is
required to ensure maximum herbicide burndown. Do not use treated crop for human or animal consumption.
Preplant
Pelargonic Acid Fruiting Vegetable Preplant
Preemergence 3-10% v/v-
(Scythe) (tomato) Directed-Shielded
Remarks:Product is a contact, nonselective, foliar applied herbicide. There is no residual control. May be tank mixed with
several soil residual compounds. Consult the label for rates. Has a greenhouse and growth structure label.

-65-

Herbicide Labeled Crops Time of Application Rate (Ibs. Al./Acre)
to Crop Mineral Muck
Rimsulfuron T o Posttransplant and -
Tomato 0.25 0.5 oz. ---
(Matrix) directed-row middles
Remarks: Matrix may be applied preemergence (seeded), postemergence, posttransplant and applied directed to row
middles. May be applied at 1-2 oz. product (0.25-0.5 oz ai) in single or sequential applications. A maximum of 4 oz.
product per acre per year may be applied. For post (weed) applications, use a non-ionic surfactant at a rate of 0.25%
v/v. for preemergence (weed) control, Matrix must be activated in the soil with sprinkler irrigation or rainfall. Check crop
rotational guidelines on label.
Sethoxydim (Poast) Tomatoes Postemergence 0.188-0.28 ---
Remarks:: Controls actively growing grass weeds. A total of 42 pts. product per acre may be applied in one season. Do not
apply within 20 days of harvest. Apply in 5 to 20 gallons of water adding 2 pts. of oil concentrate per acre. Unsatisfactory
results may occur if applied to grasses under stress. Use 0.188 Ib ai (1 pt.) to seedling grasses and up to 0.28 Ib ai (12
pts.) to perennial grasses emerging from rhizomes etc. Consult label for grass species and growth stage for best control.
Trifloxysulfuron Tomatoes
Post directed 0.007-0.014
(Envoke) (transplanted)
Remarks: Envoke can be applied at 0.1 to 0.2 oz product/A post-directed to transplanted tomatoes for control of nutsedge,
morningglory, pigweeds and other weeds listed on the label. Applications should be made prior to fruit set and at least45
days prior to harvest. A non-ionic surfactant should be added to the spray mix.
Trifluralin
(Treflan HFP)
(Treflan TR-10) Tomatoes
(Trilin) (Trilin 10G) (except Dade County) Pretransplant incorporated 0.5 ---
(Trifluralin 480)Dade ounty)
(Trifluralin 4EC)
(Trifluralin HF)
Remarks: Controls germinating annuals. Incorporate 4 inches or less within 8 hours of application. Results in Florida are
erratic on soils with low organic matter and clay contents. Note label precautions of planting non-registered crops within 5
months. Do not apply after transplanting.
Trifluralin
(Treflan HFP)
(Treflan TR-10)
(Treflan TR-10) Direct-Seeded tomatoes
(Trilin) (Trilin 10G) (except Dade County)Post directed 0.5 ---
(except Dade County)
(Trifluralin 480)
(Trifluralin 4EC)
(Trifluralin HF)
Remarks: For direct-seeded tomatoes, apply at blocking or thinning as a directed spray to the soil between the rows and
incorporate.

Row Application (6' row spacing 36" bed)4
Recommended
Broadcast Chisel Chisels Rate/1000
Product (Rate) Spacing (per Row) Rate/Acre Ft/Chisel
FUMIGANT NEMATICIDES
Methyl Bromide3 225-375 Ib 12" 3 112-187 Ibs 5.1 -8.6 Ib
67-33
Chloropicrin1 300-500 Ib 12" 3 150-250 Ibs 6.9 11.5 lb
Telone 112 9-12 gal 12" 3 4.5-9.0 gal 26 53 fl oz
Telone C-17 10.8-17.1 gal 12" 3 5.4-8.5 gal 31.8-50.2 fl oz
Telone C-35 13- 20.5 gal 12" 3 6.5-13 gal 22-45.4 fl oz
Metham Sodium 50-75 gal 5" 6 25 37.5 gal 56 111 fl oz
NON-FUMIGANT NEMATICIDES
Vydate L treat soil before or at planting with any other appropriate nematicide or a Vydate transplant water drench
followed by Vydate foliar sprays at 7-14 day intervals through the season; do not apply within 7 days of harvest; refer
to directions in appropriate "state labels", which must be in the hand of the user when applying pesticides under state
registrations.
1 If treated area is tarped, dosage may be reduced by 33%.
2 The manufacturer of Telone II, Telone C-17, and Telone C-35 has restricted use only on soils that have a relatively shallow hard pan or
soil layer restrictive to downward water movement (such as a spodic horizon) within six feet of the ground surface and are capable of
supporting seepage irrigation regardless of irrigation method employed. Higher label application rates are possible for fields with cyst-
forming nematodes. Consult manufacturers label for personal protective equipment and other use restrictions which might apply.
3 Use of methyl bromide for agricultural soil fumigation in tomato now officially occurs during the period Jan 1, 2005 to Jan 1, 2006
via international approval of a specific Florida request for a Critical Use Exemptions (CUE). Consult your local University of Florida
Cooperative Extension Service county office for additional information regarding official approved uses, soil application rates, and state
and federal reporting requirements.
4Rate/acre estimated for row treatments to help determine the approximate amounts of chemical needed per acre of field. If rows are
closer, more chemical will be needed per acre; if wider, less.
Rates are believed to be correct for products listed when applied to mineral soils. Higher rates may be required for muck (organic) soils.
Growers have the final responsibility to guarantee that each product is used in a manner consistent with the label. The information
was compiled by the author as of July 14, 2005 as a reference for the commercial Florida tomato grower. The mention of a chemical or
proprietary product in this publication does not constitute a written recommendation or an endorsement for its use by the University
of Florida, Institute of Food and Agricultural Sciences, and does not imply its approval to the exclusion of other products that may be
suitable. Products mentioned in this publication are subject to changing Environmental Protection Agency (EPA) rules, regulations, and
restrictions. Additional products may become available or approved for use.